ALBERT

Description: In this paper, the mechanical properties of nano-silica modified insulating paper under the combined action of mechanical vibration and temperature conditions are studied. Unmodified and nano-silica modified cellulose insulating paper with 2 wt% and 4 wt% were prepared, respectively, and a series of mechanical-thermal synergy experiments were carried out. With the same mechanical stress and temperature, and with the same aging duration of 144 h (6d), the tensile strength of modified insulating paper with 4 wt% nano-silica, increased 9.9 N and 5.5 N, respectively, compared with those of the unmodified and the 2 wt% nano-silica modified insulating paper. The experiments indicate that the nano-silica modification can effectively improve the mechanical properties of insulating paper. In this work, the modified mechanism of nano-silica is analyzed from the interface effect of modified polymer and the quantum effect of the modified polymer interface two aspects. It is shown that the interface formed in the modified insulating paper can transfer the mechanical stress acted on the insulating paper and prevent the cracks formed in the aging process of the test sample from further expansion, while the quantum effect discretizes the electron energy level, which can restrict the motion of the molecular chain segment to some extent. The conclusion can be used for reference to improve the performance of insulating paper.

Description: The skylight on the roof of an atrium can be popular for commercial malls to illuminate the core area of the building. However, the solar radiation and its heat can get into the building together with the daylight, causing excessive cooling load. This paper studies the daylighting and energy performances of skylight coverage area for the air-conditioned atriums in the hot and humid regions. The energy performance with different atrium heights, glass types and the coverage ratios of the skylight are studied. The daylight performance was simulated by the ray-tracing Radiance and was transferred into EnergyPlus for energy evaluations. The finding suggested that, for hot and humid climates, the skylight coverage ratio should be controlled carefully to prevent the excessive solar heat gain. When the on/off lighting control is applied, the total energy consumption of the single-floor cases (or of the top floor for the multi-floor cases) leveled off when the coverage ratio of the skylight reached 9%. Thus, the skylight is favorable to the energy saving of the low-rise or single-floor commercial buildings only under the current assumptions, as the ground of the atrium cannot be well illuminated while the excessive solar radiation gets into the building. The skylight should be shaded in cooling seasons to prevent the excessive solar heat gains.

Description: The production of liquefied natural gas (LNG) is a high energy-consuming process. The study of ways to reduce energy consumption and consequently to reduce operational costs is imperative. Toward this purpose, this study proposes a hybrid system adopting a mixed refrigerant for the liquefaction of natural gas that is precooled with an ammonia/water absorption refrigeration (AR) cycle utilizing the exhaust heat of a molten carbonate fuel cell, 700°C and 2.74 bar, coupled with a gas turbine and a bottoming Brayton super-critical carbon dioxide cycle. The inauguration of the ammonia/water AR cycle to the LNG process increases the cooling load of the cycle by 10%, providing a 28.3-MW cooling load duty while having a 0.45 coefficient of performance. Employing the hybrid system reduces energy consumption, attaining 85% overall thermal efficiency, 53% electrical efficiency and 35% fuel cell efficiency. The hybrid system produces 6300 kg.mol.h−1 of LNG and 146.55 MW of electrical power. Thereafter, exergy and sensitivity analyses are implemented and, accordingly, the fuel cell had an 83% share of the exergy destruction and the whole system obtained a 95% exergy efficiency.

Description: High speed photography by Caustics method using Cranz-Schardin camera was studied for crack propagation and divergence in thermally tempered glass. Tempered 10 mm thick glass plates were used as a specimen. Two types of bifurcation and branching as the crack divergence could be observed and clarified even in 10 mm thick tempered glass. The difference of the shadow spot sizes between bifurcation type and branching type could be confirmed.

Description: In the component operated at elevated temperatures, the life evaluation should be made in consideration of both creep and fatigue (creep-fatigue) such as the linear damage summation rule. However, the concept of creep-fatigue life evaluation has not spread well in the industry. In order to consider the reason, a series of past creep-fatigue research was surveyed, namely experimental methods, life evaluation procedures and strength design guidelines. As a result, it was revealed that the mechanism of creep-fatigue interaction has not been fully clarified yet, which results in obscuring the necessity of creep-fatigue life evaluation. The necessity of creep-fatigue life evaluation was reviewed and consequently it proved to be necessary in two cases. One is the case where the creep-fatigue interaction is significant for some kinds of material, loading modes and temperatures. The other is one where the amount of creep damage is almost the same as that of fatigue damage even though the creep-fatigue interaction is insignificant.

Description: According to the regulation of European Union laws in 2014, it was inevitable to switch to low global warming potential (GWP) fluids in the refrigeration systems where the R404A working fluid is currently used. The GWP of R404A is very high, and the potential for ozone depletion is zero. In this study, energetic and exergetic performance assessment of a theoretical refrigeration system was carried out for R404 refrigerant and its alternatives, comparatively. The analyses were made for R448A, R449A, R452A and R404A. The results of the analysis were presented separately in the tables and graphs. According to the results, the cooling system working with R448A exhibited the best performance with a coefficient of performance (COP) value of 2.467 within the alternatives of R404A followed by R449A and R452A, where the COP values were calculated as 2.419 and 2.313, respectively. In addition, the exergy efficiencies of the system were calculated as 20.62%, 20.22% and 19.33% for R448A, R449A and R452A, respectively. For the base calculations made for R404A, the COP of the system was estimated as 2.477, where the exergy efficiency was 20.71%. Under the same operating conditions, the total exergy destruction rates for R404A, R448A, R449A and R452A working fluids were found to be 3.201 kW, 3.217 kW, 3.298 kW and 3.488 kW, respectively. Furthermore, parametric analyses were carried out in order to investigate the effects of different system parameters such as evaporator and condenser temperature.

Description: By incorporating the merits of partitioned stator and flux modulation techniques, the partitioned stator flux modulation motors featuring high torque, have attracted much attention. This paper investigates four partitioned stator flux modulation motors with different types of PM arrays, including surface-mounted type, consequent-pole type, Halbach-array type, and half-Halbach type. The influences of key parameters on the average electromagnetic torque is conducted and compared. Then, based on the optimal designs, four motors are compared in terms of magnetic field distribution, back-electromotive force, torque characteristics, loss and overload ability. The result reveals that the half-Halbach motor is capable of utilizing more PM to improve electromagnetic torque. Also, the consequent-pole motor achieves the highest torque per PM usage. In addition, performance comparison under the same PM usage is carried out. The result shows that the half-Halbach motor not only exhibits the highest average torque but also achieves the highest PM utilization. Last, the prototype of half-Halbach motor is built for experimental verification.

Description: In electric motorcycles and light electric cars, permanent magnetic synchronous motor (PMSM) of outer-rotor type are preferred, due to its concise structure and flexible control. Since the body mass and road impact causes vertical eccentricity on shaft bearings, vibration and noise take place during vehicle cruising along with a torque and speed ripple. The torque ripples contain significant features closely related to eccentricity, and those special components can be compensated by an injection current with proper frequency, phase and amplitude. In this paper, a novel control method is used to regulate the injection current to restrain torque ripples. By coarse turning with quadratic spline curve fitting and fine turning with successive approximation, the method can response sudden disturbance and drive the specific torque ripple to minimum in a very short time, so that the performance on ride comfort and handling stability of the vehicle could be improved. Experimental tests show that the method performs favorably with rapid convergence and validity.

Description: The yokeless and segmented armature axial-flux in-wheel motor with amorphous magnet metal (AMM) stator segment has the advantage of low iron losses, but its open-slot structure causes high eddy-current losses of the permanent magnet (PM), which reduces the efficiency and reliability of the in-wheel motor. To avoid the demagnetization caused by the heat generated by PM losses, the mechanism of PM eddy-current losses reduction for the axial-flux in-wheel motor is revealed by the calculation model. In this paper, the time-step three-dimensional finite-element method (3-D FEM) is used to analyze the PM eddy-current loss caused by slotting effects, spatial harmonics, and time harmonics at different speeds. The effect of PM skewing, PM segmentation, and soft magnetic composite (SMC) layer inserted on the top of PM on eddy-current losses are compared. These methods cannot simultaneously meet the requirements of PM losses reduction and the electromagnetic performance of the motor. A novel combined stator segment with the SMC brim arranged on the top of the AMM stator teeth is proposed to improve the amplitude and distribution of the PM eddy-current density. The analysis results show that the combined stator segment can significantly reduce the PM eddy-current loss and improve the electromagnetic performance of the in-wheel motor.

Description: The continuously variable transmission (CVT) clumped system with lots of nonlinear uncertainties operated by the six-phase induction motor (SIM) is lacking in good control performance for using the linear control. In light of good ability of learning for nonlinear uncertainties, the sage dynamic control system using mixed modified recurrent Rogers–Szego polynomials neural network (MMRRSPNN) control and revised grey wolf optimization (RGWO) with two adjusted factors is proposed to acquire better control performance. The MMRRSPNN control and RGWO with two adjusted factors can execute intendant control, modified recurrent Rogers–Szego polynomials neural network (MRRSPNN) control with a fitted learning rule, and repay control with an evaluated rule. In addition, in the light of the Lyapunov stability theorem, the fitted learning rule in the MRRSPNN and the evaluated rule of the repay control are founded. Besides, the RGWO with two adjusted factors yields two changeable learning rates for two weights parameters to find two optimal values and to speed-up convergence of two weights parameters. Experimental results in comparisons with those control systems are demonstrated to confirm that the proposed control system can achieve better control performance.

Description: The safety and reliable operation of power grid is directly related to the ability of power transformer to withstand short-circuit, therefore, it is a problem to be solved to improve the ability of large power transformer windings to withstand short-circuit. Taking a three-phase five-limb power transformer as an example, the transient electromagnetic field, short-circuit electrodynamics force of windings and mechanical strength of coils are analyzed in depth. Firstly, the three-dimensional finite element model of the prototype is established, and the magnetic flux density distribution of the three-dimensional transient electromagnetic field of transformer under short-circuit operation and the axial and radial static force magnitude of the winding are calculated by using the field-circuit coupling method, and the distribution law can be obtained. At the same time, the mechanical strength of power transformer winding in its height direction is discussed, and the modal vibration mathematical model of transformer low-voltage winding in Z-axis direction is established. The displacement change and resonance frequency of the winding wire cake in the axial direction caused by short-circuit are calculated, and the short-circuit electrodynamics force of the winding is also checked. The research in this paper provides a theoretical basis for strengthening the design of short-circuit withstanding capacity of windings, and has a certain theoretical and engineering application value.

Description: This paper presents the cogging torque calculation in radial-flux surface-mounted permanent-magnet machines based on energy approach, air-gap flux density and permeance functions. Magnet segmentation and teeth notching are two important techniques in reducing the cogging torque, so in this paper an analytical approach is investigated to model these effects on the produced cogging torque. This approach employs new methods to model the teeth notch and PM segments based on Fourier expansion and simplified flux distribution. The analysis results and comparisons verify the validity of the model that has advantages in sensitivity analysis and structure optimizations of surface-mounted permanent-magnet machines from the aspect of cogging torque. This model could be extended for other types of PM electrical machines.

Description: A pseudo density topology optimization approach is introduced in nonlinear electromagnetism, which follows the SIMP (Solid Isotropic Material with Penalization) method. The adjoint approach is used to arrive at the sensitivity of the objective function. The elaborated optimization procedure includes nonlinearity of the ferromagnetic material. On the other hand, an applied linear characteristic of the ferromagnetic material results in a too small or wrong electromagnetic actuator dimension. Non-conforming grids are used to achieve a high accuracy by computing the discrete form. At the same time the number of finite elements decreases strongly. The implementation is applied to an electromagnetic actuator in 2D and 3D.

Description: As a renewable energy, ocean wave energy is exploited with infinite potential to solve the energy crisis. In this study, we develop a novel two-body direct-drive wave energy converter (DD-WEC) to surmount the problems associated with low power density, low direct-drive speed of the buoys, seawater corrosion and maintenance in the existing two-body WEC. Its prototype consists of two cylindrical buoys that float horizontally at sea level and the Halbach permanent magnet linear generator (HPMLG) that is employed in the power take-off (PTO) system. The energy is extracted from the relative motion between two buoys oscillating. Compared with the existing WEC, the proposed WEC has more vigorous motion between buoys, higher conversion efficiency and little extra underwater structure, due to the utilization of the horizontal buoys and the HPMLG. First, the motion equations of buoys are derived on the basis of linear wave theory. And depending on the motion equations, the structure of buoys and the HPMLG is designed. And we found that compared with the existing WEC, the proposed WEC has more vigorous motion between buoys in the seawater waves oscillation. Then, based on finite-element method (FEM), the performance of the HPMLG is evaluated, and it can generate 19% more power than the traditional permanent magnet linear generator (TPMLG) based on the same wave motion. Finally, the DD-WEC prototype is manufactured based on the designed parameter. The manufactured prototype is tested in the test platform and the wave tank. The measured output voltage is highly consistent with the observed variation trends in FEM simulation data. The results show that the proposed DD-WEC is well suited for wave energy conversion.

Description: Due to use of cans in the airgap, the eddy current induction occurs and generates can loss. The loss on cans is considerably high and leads to excessive temperature rise of a canned motor, a fast and accurate temperature is necessary. In this paper, a compensation element assisted thermal model is proposed and stressed, due to the inaccuracy of tradition thermal network model. First, the studied canned motor is described. Second, the thermal analysis principle is studied. Then, the novel thermal network model with compensation element is studied, with thermal resistance calculation. Finally, compare motor temperature that is measured by thermal network model and finite element (FE). FE is used as reference and complement.

Description: The aim of this paper is to emphasize the influence of the magnetization vector misalignment to the magnetic force. In this concrete example the force between permanent ring magnet and soft magnetic cylinder was analyzed. Configuration that can be seen in different devices that incorporate permanent magnets. Magnetic force between permanent ring magnet and soft magnetic cylinder is calculated using hybrid boundary element method and semi-analytical approach based on fictitious magnetization charges. By selecting the angle of the magnetization vector inclination, obtained expression can be used for the force calculation of axially or radially magnetized permanent magnet and magnetic body of finite dimension.

Description: This letter presents a bistable permanent magnet actuator, based on double wing magnetic flux (DWMF) formed by the structure of welding sleeve and slotted armature. The double wing magnetic flux consist of high wing magnetic flux (HWMF) and low wing magnetic flux (LWMF), resulting in bistable performance under differentiating control. Parameters improvement around DWMF is analyzed based on modeling, and optimized results for a prototype actuator are obtained. The experimental and simulation results agree well, and show that the prototype actuator can realize bistable performance under the DC step voltage drive, with the holding force of 8.2 N (without current) and the restoring force of −31.7 N (with negative current), the dynamic results show that the displacement response time within 8 mm is 28 ms, of which the actuation time is 16.5 ms, the transient maximum power consumption of the restoring period is 18 W.

Description: Due to the lack of suitable evaluation systems for heating, ventilation, air-conditioning (HVAC) systems with ground source heat pump (GSHP) and energy storage (ES) technologies, it is difficult to design a building HVAC system to achieve optimized design with regard to investment cost, energy saving and environmental protection. This is a study on developing a fuzzy evaluation system by including GSHP and ES with comprehensively determined weights into an HVAC system. A questionnaire method was used and the answers from 21 HVAC experts were analyzed to facilitate the modeling. Taking a commercial integrated project in Nanjing as an engineering case, the evaluation system was tested. If the system with a comprehensive merit value of 0.303 is adopted, the annual operating cost is reduced by 32.5%, the annual total life cycle cost is reduced by 26.5% and the primary energy consumption and carbon emissions are reduced by 10.5%, with the initial investment increased by 6.5%. This study revealed that the newly developed evaluation system is very useful for realizing the optimal design of HVAC systems.

Description: Precision machining fields require the worktable to have a large-scale multi-degree-of-freedom motion capability. In order to provide a more accurate magnetic model for the control strategy decoupling process and the size parameter optimization design process of the maglev rotary table. This paper proposes a new magnetic modeling method based on the Two-Dimensional Harmonic method. Different from the existing harmonic method, this method simultaneously considers the tangential and radial magnetic field changes of circumferential magnetic array. And it eliminates the edge effect of the magnetic flux density distribution in the radial aperiodic direction. The magnetic force and torque are solved by the Lorenz integral formula and the Gaussian quadrature method. In order to verify the accuracy of the TDH method, the boundary element software RadiaTM is used for simulation, and a prototype is made for measurement. The experimental results shown that this method reduced the maximum error of the radial edge magnetic field from 104.19% to 3.29%. And it improved the calculation accuracy of magnetic force and torque by 60.74% and 84.39% respectively. This method does not rely on special example, and is beneficial to cross-platform applications. It is more suitable for realizing the magnetic modeling of the maglev rotary table with both rotational motion and large-stroke translational motion.

Description: Synchronous Reluctance Motors (SynRMs) have been widely used in some industrial fields because of their attractive characteristics, such as high efficiency, low cost, and simple structure. In order to reduce the torque ripple of the SynRMs, a non-parametric model is usually used to optimize the rotor structure. However, the conventional method has the problems of the low-accuracy and poor generalization ability. In this paper, an optimization method of the rotor structure is proposed to reduce the torque ripple by utilizing the deep learning algorithm. Firstly, the sample data of the relationship between the rotor structural parameters and torque ripple are obtained with the finite element analysis (FEA). The fast calculation model is established by the deep neural network (DNN). Then, with the goal of not weakening the torque density and minimizing the torque ripple, the immune clone algorithm (ICA) is utilized to optimize the structural parameters of the rotor at different operating points. Finally, the correctness and validity of the method are verified by the simulation analysis. It is concluded that the accuracy of the model established by DNN is acceptable. The proposed method can significantly reduce the torque ripple and increase the torque density.

Description: Obtaining the constant force at a given current benefits its applications in diverse fields. However, not depending on displacements, such a force characteristic is not available easily since this force is determined by a specific structure, materials, geometrical parameters and others. Therefore, utilizing the finite element method (FEM), the electro-magnet force of a proportional electro-magnet located at a semi-active damper is calculated considering different parameters, further obtaining better choices of crucial parameters for achieving the constant force and independence of displacements. Finally reflected through the maximum fluctuation of 0.82 N and the maximum error of 0.9 N compared to experimental results, a proportional electro-magnet with force characteristics of relatively high accuracy has been achieved.

Description: Permanent magnet machine adopting Halbach array has more sinusoidal air-gap flux density distribution and higher air-gap flux density magnitude. Compared with the equal segmented Halbach array, the fundamental magnitude of air gap flux density can be higher and distortion rate can be lower by reasonably designing each segment width in unequal segmented Halbach array. Thus, in this paper, the permanent magnet machine adopting unequal segmented Halbach array is researched. Firstly, an analytical model is established for PM machine adopting Halbach array to improve the calculation efficiency. This analytical model can be applied to the Halbach array having arbitrary pole pair number, arbitrary number of segments per pole, arbitrary segment width and arbitrary gap width between segments. Further, the calculation results for air gap flux density between analytical model and finite element method are compared to verify the analytical model. In addition, the method to determine each segment width in the unequal segmented Halbach array is proposed firstly in this paper. On this basis, effects of the gap width between segments and each segment width under one pole on air gap flux density are researched. The research conclusions will provide guidance for the design and fabrication of unequal segmented Halbach array.

Description: In this paper, a high-energy density electromagnetic buffer (EMB) is studied and analysed for the violent acceleration and high velocity of intensive impact loads. First, the design requirements of the EMB are proposed to select reasonable structure and magnetic circuit parameters. The equivalent current model is used to introduce the primary eddy current affected by demagnetization effect and the induced secondary eddy current. The magnetization process is studied by dividing the conductor tube into the approach end and the departure end. Considering the nonlinear damping and eddy current interaction between primary and secondary, a primary-secondary eddy current loss coupled nonlinear time-step finite element model (FEM) is established to obtain the spatiotemporal distribution characteristics of eddy current. Finally, a test experiment with weak impact, medium impact and intensive impact was carried out. The measured displacement, velocity, damping force, and time nodes responses during buffering are consistent with the established time-step FEM results. The proposed high-energy density EMB can effectively complete the impact buffering process. It is reasonable to obtain the eddy current loss and its magnetization law from the established FEM which is suitable for shock buffering with different impulse strength.

Description: Among non-toxic and inflammable working fluids, carbon dioxide (CO2) proving a possible choice of refrigerant is gaining full status because of its reducing capacity of global warming and ozone depletion. Heat pump (HP) equipment uses energy more rationally to heat water by reducing emissions and global warming caused by conventional refrigerants. HP capability demands an environmentally friendly refrigerant for their full utilization and high energy saving as well to attaining higher coefficient of performance (COP) without much design corrections. CO2 is checked for sustainability to eliminate the standardized refrigerants such as chlorofluorocarbons (CFC) and hydro-CFC. In this work, the performance of CO2 as an alternate refrigerant in HP for heating water at different pressure, flow rates, evaporator fan speed and preheating have been investigated. HP is accommodated with two condensers. The results showed that the increased mass flow rate had increased COP, overall heat transfer (HT) coefficient (U) and HT. However, logarithmic mean temperature difference was decreased for increasing evaporator’s fan speed and pressure. The outlet water temperature (TWO) of second condenser increased with decreasing water flow rate. Improved COP, HT and TWO of HP are observed from the experimental evaluation in case of preheating of water.

Description: By using power electronic devices, photovoltaic grid-connected power generation may inject harmonics into the power system. As the photovoltaic grid-connected inverter has the same basic structure as the active power filter, so the unified control of the photovoltaic grid and active filtering can be achieved. When the current unified control system compensates harmonics of the grid side, it mainly uses ip-iq harmonic detection method, which is based on instantaneous reactive power theory. When the three-phase voltage is unbalanced, the method has a large voltage phase angle detection error and the signal of the low-pass filter tracking system is long, detection time delay and even failure occur. This paper proposes an improved fast harmonic detection method. When phase deviation or amplitude change occurs to the three-phase voltage, the positive and negative-sequence voltages are simultaneously park transformed. The negative-sequence component is filtered by the current average module to obtain the fundamental amount of the voltage, then the phase angle of the positive-sequence voltage is accurately calculated to improve the harmonic current detection accuracy. Through the study of the integral method, it is found that the least common multiple of each harmonic period can be used as the integral interval, and the integral value is also zero, so the detection delay time is reduced by replacing the low-pass filter with an integration module. The simulation results show that the proposed harmonic detection algorithm can accurately detect harmonics when the three-phase voltage is unbalanced, and about 0.057 s improve the harmonic detection speed compared with the commonly used ip-iq method.

Description: The objective of the work is to derive analytical solutions based on the Riemann–Hilbert (R–H) approach for semipermeable strip saturated two unequal collinear cracks in arbitrary polarized piezoelectric media. We particularly consider the influence of far field electromechanical loadings, poling direction and different crack-face boundary conditions. The problem is mathematically formulated into a set of non-homogeneous R–H problems in terms of complex potential functions (related to field components) using complex variable and extended Stroh formalism approach. After solving these equations, explicit solutions are obtained for the involved unknown complex potential functions and hence, the stress and electric displacement components at any point within the domain. Furthermore, after employing standard limiting conditions, explicit expressions for some conventional fracture parameters such as saturated zone lengths (in terms of nonlinear equations), local stress intensity factors and crack opening displacement are obtained. Numerical studies are presented for the PZT-4H material to analyze the effects of prescribed electromechanical loadings, inter-cracks distance, crack-face conditions and poling direction on the defined fracture parameters.

Description: Lithium-ion batteries retired from electric vehicles can provide considerable economic benefits when they are retired for secondary use. However, retired batteries after screening and restructuring still face the problem of inaccurate battery pack state-of-charge (SOC) estimation due to the existence of extreme inconsistency. To solve this problem, an adaptive fading unscented Kalman filtering (AFUKF) algorithm based on the cell difference model (CDM) is proposed in this paper for improving the accuracy of SOC estimation of retired lithium-ion battery packs. Firstly, an improved CDM based on a hypothetical Rint model is developed based on a second-order resistor/capacitor equivalent circuit model. Secondly, an AFUKF algorithm is developed to improve the adaptability and robustness of local state estimation against process modelling errors. Finally, characteristic data are obtained by conducting discharge tests on the screened retired lithium-ion batteries under specific operating conditions. The proposed method can improve the accuracy of SOC estimation of retired lithium-ion battery packs and provide a new idea for SOC estimation of retired lithium-ion battery packs, as shown by the simulated real experimental data.

Description: This paper presented a novel analytical method for calculating magnetic field in the slotted air gap of spoke-type permanent-magnet machines using conformal mapping. Firstly, flux density without slots and complex relative air-gap permeance of slotted air gap are derived from conformal transformation separately. Secondly, they are combined in order to obtain normalized flux density taking account into the slots effect. The finite element (FE) results confirmed the validity of the analytical method for predicting magnetic field and back electromotive force (BEMF) in the slotted air gap of spoke-type permanent-magnet machines. In comparison with FE result, the analytical solution yields higher peak value of cogging torque.

Description: Aiming at the “light wind start, light wind power generation” of vertical axis wind turbine, a new T-shaped radial passive magnetic bearing with high suspension characteristics is proposed. Passive magnetic bearings used in vertical axis wind turbines usually have small bearing capacity and difficult magnetization. The new T-shaped radial PMB can improve the radial bearing capacity, and the three magnetic rings all adopt simple axial magnetization. The new T-shaped radial PMB is combined with mechanical auxiliary bearing to form the suspension system of wind turbine. In the stable state, the suspension system can realize radial and axial stable suspension. The structure and working principle of the suspension system are briefly described. Through the finite element simulation, the characteristics of the new T-shaped radial PMB, the traditional double-ring PMB and the T-shaped PMBs are compared. Taking the high bearing capacity and high stiffness of the new T-shaped radial PMB as the optimization objective, the multi-objective optimization of the new T-shaped radial PMB was carried out by changing its geometric parameters (inner diameter, magnetization length and air gap). The research results show that: Under the same bearing capacity, the volume of the new T-shaped radial PMB is reduced by about 78.64%. Under the same volume, its bearing capacity increased by about 30.7%, and its stiffness increased by about 96.1%. After optimization, its radial bearing capacity increased to 101.38 N, and its stiffness increased to 202.76 N/mm.

Description: Free-piston engine coupled with linear generator is a new type of thermoelectric energy converter, which has the advantages of high efficiency and simple structure. In this paper, a novel moving-coil linear generator with dual axial-magnetized stator is proposed for this kind of short-stroke high frequency oscillation generating applications. Finite-element (FE) model of the generator is created, the static and transient characteristics are analyzed, and the losses in different components are compared. A full-bridge power converter is designed to meet the control requirements of reversible operation. A 540 W experimental prototype is developed and tested to validate the FE analysis. According to the tested and simulated results, the generator has advantages of high efficiency and fast response. The generating efficiency of 92% can be obtained at the rated generating power. The average inductance of the proposed generator is about 0.7 mH, which benefits from the low armature effect and ensures a very quick electromagnetic response.

Description: In this paper, the concept of body of revolution (BOR) finite-difference time-domain method time-domain (BOR-FDTD) method is applied to symplectic multi-resolution time-domain (SMRTD) algorithm to propose a BOR-SMRTD method. In order to solve the problem that the obliquely incident pulse wave cannot be directly introduced into BOR-SMRTD method, an efficient one-dimensional time-domain algorithm for propagating obliquely incident pulse plane wave in BOR-SMRTD method is also proposed. The numerical results show that the proposed algorithm runs 51 times faster than the algorithm based on fast Fourier transform (FFT) completely. Moreover, the scattering problem of a perfect electric conductor (PEC) cylinder with finite length is calculated to verify the effectiveness of the algorithm. The surface current density distribution along a generatrix of the cylinder at a giving frequency was extracted, and the results are in good agreement with that obtained with the methods of moment (MoM) and BOR-FDTD. Finally, the radar cross section (RCS) of a PEC sphere was calculated, and the results agree well with the theoretical values.

Description: The live working paths for equipotential operators in the hanging basket method is determined by minimum safety values of various clearances stipulated in regulations. However, the optimization of the safety path planning by the complex gaps is scarce. In this paper, an optimization method for path planning is proposed based on ant colony algorithm. Grid model is established to partition the operation area into different calculation districts, in which key parameters are grid data and obstacle grids. Grid data are the maximum value of the electric field strength on the body surface, calculated by the finite element model. And obstacle grids are grids that dissatisfy the requirements of complex gaps and their data are larger than the air breakdown field strength. Then ant colony algorithm is employed to search for the best operation path with the minimum working distance and the minimum electric field strength value. After that, an application case is illustrated to demonstrate the optimizing processes. At last, the shock U50 test and power frequency corona discharge test are implemented to verify the safety of the optimized path. Therefore, the path obtained by the proposed method scientifically and effectively shortens the distance of the hanging basket method.

Description: In this paper, the lightning return stroke electromagnetic field at close distance is calculated by the way of transmission line (TL) model and full-wave three-dimensional electromagnetic field simulation software XFDTD, which is based on finite-difference time-domain (FDTD) method. The evolution of distributions of electric field and magnetic field are summarized in the study. Furthermore, the total electromagnetic field and major components are analyzed to clarify the electromagnetic hazard from lightning electromagnetic pulse (LEMP). Then the temporal and spatial distribution characteristic of Poynting vector of the electromagnetic environment is shown to expound the energy distribution of LEMP at close distance. The results based on the analyses of field strength and Poynting vector show that the distribution of electric field, magnetic field and Poynting vector at close distance is akin to multilayered cylinder, and LEMP in the region characterized by large amplitude, transient behavior and high electromagnetic energy is a potential threat to adjacent electronic equipments. Moreover, engineering basis concerning LEMP protection and electromagnetic compatibility (EMC) design in the region closed to the return stroke point can be provided by the synthetical analysis of LEMP.

Description: Unsteady viscous two-dimensional magnetohydrodynamic micropolar flow, heat and mass transfer from an infinite vertical surface with Hall and Ion-slip currents is investigated theoretically and numerically. The simulation presented is motivated by electro-conductive polymer (ECP) materials processing in which multiple electromagnetic effects arise. The primitive boundary layer conservation equations are transformed into a non-similar system of coupled non-dimensional momentum, angular momentum, energy and concentration equations, with appropriate boundary conditions. The resulting two-point boundary value problem is solved numerically by an exceptionally stable and well-tested implicit finite difference technique. A stability analysis is included for restrictions of the implicit finite difference method (FDM) employed. Validation with a Galerkin finite element method (FEM) technique is included. The influence of various parameters is presented graphically on primary and secondary shear stress, Nusselt number, Sherwood number and wall couple stress. Secondary (cross flow) shear stress is strongly enhanced with greater magnetic parameter (Hartmann number) and micropolar wall couple stress is also weakly enhanced for small time values with Hartmann number. Increasing thermo-diffusive Soret number suppresses both Nusselt and Sherwood numbers whereas it elevates both primary and secondary shear stress and at larger time values also increases the couple stress. Secondary shear stress is strongly boosted with Hall parameter. Ion slip effect induces a weak modification in primary and secondary shear stress distributions. The present study is relevant to electroconductive non-Newtonian (magnetic polymer) materials processing systems.

Description: This paper analyzes the steady boundary layer flow and heat transfer of biomagnetic fluid over a stretching/shrinking sheet with prescribed surface heat flux under the influence of a magnetic dipole. The governing equations are transformed into a set of ordinary differential equations (ODEs) by using similarity transformations. Numerical results are obtained using the boundary value problem solver bvp4c of MATLAB. The effects of various physical parameters on the velocity and temperature profiles as well as skin friction coefficient are discussed. The paper shows that dual solutions exist for certain values of stretching/shrinking sheet and suction parameters. Stability analysis is performed to determine which solution is stable and physically valid. Results of the stability analysis depict that the first solution (upper branch) is stable and physically realizable, while the second solution (lower branch) is unstable.

Description: Soft-switched wireless power transfer system combines the advantages of both wireless power transfer (WPT) and soft-switching technology. In WPT systems, high-frequency power electronic converters are crucial part for coupling/decoupling to transfer power from sending end to receiving end without any physical contact. Soft-switching of power electronic converters can mitigate conduction losses and increase the efficiency. This paper comprises of the technical review and advancements in the technological developments of soft-switched wireless power transfer systems. This work identifies and validates the trends and challenges related to soft-switched wireless power transfer system in the current scenario. This study establishes that reaping the benefits of this technology will need a few more years of research and development. Characterization of various methods and results found in literature for various application are discussed in detail, which provides an in-depth summary of soft-switched wireless power transfer design aspects.

Description: Accurate prediction of electricity sale has a positive effect on power companies in rationally arranging power supply plans, scientifically optimizing power resource allocation, improving power management efficiency, saving energy and reducing consumption. Predicting future electricity sale based on historical electricity sale data can essentially be summarized as a time series forecasting problem. This paper proposes a fast and memory-efficient method, which adopts the expressive power of deep neural networks and the time characteristics of sequence-to-sequence structure (parallel convolution and recurrent neural network) for long range forecasting in electricity sale. Through a large number of experiments and evaluation of real-world datasets, the effectiveness of the proposed method is proved and verified in terms of prediction accuracy, time consuming and training speed.

Description: Electromagnetic linear actuators (ELAs) may be confronted with unsatisfactory performance when subjected to overheating. Therefore, it is significant to clarify its thermal characteristics and design the thermal performance requirements. A thermal analysis method based on multiphysics coupling model was presented, which uses the non-simplified loss distribution as the heat source to calculate the temperature field, adjusts the material properties by temperature, and considers the interaction between motion (including impact) and loss. More importantly, an improved universal equivalent winding to satisfy the condition of real compact concentrated winding was developed. Finally, the validity of this approach was verified through the experiment, and the regularity of temperature was summarized. The results show that the error of simulation and experiment is less than 6% and the permissible continuous operation frequency is no more than 30 Hz. The approach proposed in this paper can be employed not only to the ELA, but also to the design and analysis a wide range of electromagnetic machines.

Description: Nowadays, the global energy and environmental problems are becoming more and more serious, which promotes the development and utilization of renewable and clean energy in various countries. Intelligent car involves many subjects such as electronic technology, artificial intelligence, automatic control technology, sensor technology and computer technology and has become an important part of the application of artificial intelligence. Solar cell is a necessary part of the normal operation of the solar intelligent car, which can provide clean energy for the intelligent car. In this paper, the image recognition technology is used to design the intelligent vehicle control system. According to the intelligent vehicle path recognition, the scale invariant feature transform (SIFT) algorithm is improved to improve the accuracy of intelligent vehicle recognition. Data fusion is used to process the data detected by multi-sensor, and the running state of intelligent vehicle is studied. An evaluation method of intelligent vehicle navigation parameters based on association rules and belief network is proposed. The maximum power point tracking control is realized by using the interference observation method to ensure that the intelligent vehicle can track the maximum power point of the solar cell.

Description: The purpose of this paper is to investogate the ectromagnetic and micropolar properties on biviscosity fluid flow with heat and mass transfer through a non-Darcy porous medium. Morever, The heat source, viscous dissipation, thermal diffusion and chemical reaction are taken into consideration. The system of non linear equations which govern the motion is transformed into ordinary differential equations by using a suitable similarity transformations. These equations are solved by making use of Rung–Kutta–Merson method in a shooting and matching technique. The numerical solutions of the velocity, microtation velocity, temperature and concentration are obtained as a functions of the physical parameters of the problem. Moreover the effects of these parameters on these solutions are discussed numerically and depicted graphically. It is found that the microtation velocity increases or deceases as the electric parameter, Hartman parameter and the microrotation parameter increase. Morever, the temperature increases as Forschheimer number, Eckert number increase.

Description: This paper focus on a state feedback controller (SFC)-based optimal control scheme for surface-mounted permanent-magnet synchronous motor (SPMSM) with auto-tuning of controller built on seeker optimization algorithm (SOA). First, based on the nonlinear state-space model of SPMSM, voltage feedforward compensation is used to design a linear SFC. Then in order to guarantee the steady performance in speed and current, integral models considering the errors of rotor speed and current response in d-axis are added in the state space model of SPMSM. Furthermore, by statically decoupling the load torque in the state equation, feedforward compensation is implemented on the load torque to improve the dynamic performance of the controller. The load torque is estimated by using disturbance observer with reasonable parameter selection. Then, with the consideration of the search capacity of seeker optimization algorithm (SOA), it is adopted to acquire matrix coefficient of the presented controller. Furthermore, in order to suppress the speed overshoot, a penalty term is introduced to the fitness index. The performance of the proposed method has been validated experimentally and compared with the conventional method under different conditions.

Description: The transfer energy of a magnetorheological fluid (MRF) coupling can be dynamically regulated by changing the MRF mechanical properties of its input and output shafts. In addition, the dynamic characteristics of its drive system can automatically be in the tune with its load characteristics to effectively suppress vibration and shock responses, to achieve overload protection of the system, and to improve its mechanical performance and safety reliability. However, the weak mechanical properties of MRF materials result in so small a coupling torque density that the MRF coupling applications for high-torque transfer is restricted. Thus, to increase the coupling torque density is becoming an urgent key technological challenge in this field. A technique based on shear-pressure mixed mode was proposed here to increase the torque density by utilizing the formation mechanism of MRF arc flux linkage. Futhermore, a new high torque arc multi-disk MRF coupling structure was designed and its corresponding mechanical torque transfer model was established. A FEA electromagnetic simulation was performed to study the distribution of the magnetic field in the MRF chamber under different current excitations. Effects of the key parameters of the elliptical arc on its transfer torque were also investigated. Finally, experimental analysis of the mechanical properties of the elliptical disk MRF coupling was conducted to verify the feasibility of the proposed technique and the validity of the torque transfer model.

Description: Due to the poor conversion efficiency and signal-to-noise ratio (SNR) of Electromagnetic Acoustic Transducer (EMAT) testing, the defect detection sensitivity is limited, which restricts the extensive industrial applications. A finite element model for the testing process of a meander-coil EMAT was established that considers the simplified excitation and detection circuits for the EMAT. Based on this model, the effect of the connection methods (parallel or series) of the coils in the generating and receiving EMATs on their generating and receiving efficiency was investigated, and the simulation results were validated experimentally. Subsequently, the pulse compression technique with a 13-bit Barker code was used for the EMAT detection, and improvements of the SNR and range resolution were established through numerical simulation and experimental measurement. The results show that compared with the traditional EMAT design, which comprises single-layer transmitting and receiving coils, the conversion efficiency of the optimized EMAT with two excitation and receiving coils in the parallel connection can be improved by 52.8%. With the application of the Barker-coded pulse compression to detect the ultrasonic A-scan signal with no synchronous average, the SNR of the defect echo can be improved by 9.5 dB compared with the A-scan signal with 128 synchronous averages.

Description: In this paper, the conformal finite-difference time-domain (CFDTD) technique and the concept of effective dielectric constant are applied to symplectic multi-resolution time-domain (SMRTD) algorithm based on Daubechies scaling functions, resulting in a conformal SMRTD (C-SMRTD) method. Moreover, a novel implementation of perfect matched layer with auxiliary differential equation (ADE-PML) is presented for the SMRTD method. Numerical results of the radar cross section (RCS) of a dielectric sphere verify the effectiveness of the C-SMRTD method, which shows good agreement with the results derived by analytical methods. It is also shown that the accuracy of the C-SMRTD method has been significantly improved compared with the MRTD method with step approximation, and the proposed method has an advantage over CFDTD at saving the CPU time and memory. Furthermore, a vault-top tunnel model is established with the proposed method, and the characteristic of the field cross-section distribution of the electromagnetic pulse (EMP) propagation in the tunnel model is also presented and discussed.

Description: In this work, we focused on the peristaltic unsteady flow of non-Newtonian nanofluid with heat transfer through a non-uniform vertical duct. The flow obeys Herschel Bulkley model through a non-Darcy porous medium under the effects of mixed convection and thermal diffusion. Moreover, the effects of thermal radiation, heat generation, Ohmic dissipation, chemical reaction and uniform external magnetic field are investigated. The derived equations that describe the velocity, temperature and nanoparticles concentration are simplified under the assumptions of long wave length and low Reynolds number. These equations have been solved by using a numerical technique with the help of shooting method. The obtained solutions are functions of the physical parameters entering the problem. The effects of these parameters and the obtained solutions are explained and discussed through a set of graphs. It is found that the increment in Prandtl number or Thermophoresis parameter reduces the spread of the nanoparticles (concentration increased) within the fluid along with the thermal diffusivity through the fluid layers. Also the non-Darcy effect supports the inertial forces, and in order to maintain Reynolds number, the viscous forces are motivated and the axial velocity is damped. Moreover, for the validation of the current methodology, this model is reduced to power law model (no yield stress) and compared with the work of Eldabe et al. [16].

Description: An experimental study was undertaken to evaluate the mathematical modelling of the magnetorheological (MR) damper featuring annular radial gap on its valve. The experiment was conducted using a fatigue dynamic test machine under particular excitation frequency and amplitude to get force-velocity and force-displament characteristics. Meanwhile, the mathematical modelling was done using quasi-steady modelling approach. Simulation using adaptive neuro fuzzy inference (ANFIS) Algorithm (Gaussian and Generalized Bell) were also carried out to portray the damping force-displacement modelling that is used to compare with the experimental results. The experimental characteristics show that amplitudes excitation and current input affect the result damping force value. The comparison of the experimental and mathematical results presented in this paper shows a significant difference in damping force value and that the quasi-steady modelling could not significantly approach the damping force-velocity results. Moreover, the semi-active damper is compared to the passive damper. The results show that a semi-active damper performs better than a passive damper because it only requires a little power. Based on the damping force-displacement modelling, it can be seen that Gaussian has a higher accuracy rather than Generalized Bell. Discussion on the energy dissipation and equivalent damping coefficient were also accomodated in this paper. Having completed in mathematical modelling and simulation, the damper would be ready for further work in-vehicle application that is development of control system.

Description: In order to solve the problem of short service life (2 months) and zero leakage of air cylinder in aerospace engineering, this paper innovatively designs a magnetic fluid sealing device of air cylinder in aerospace engineering through magnetic circuit analysis and magnetic fluid sealing theory. The magnetic field finite element method is used to calculate the magnetic field distribution in the sealing gap under different key parameters such as the number of pole teeth, the height of the radial sealing gap, the thickness of the permanent magnet, the slot width, the ratio of pole piece height to shaft. And numerical analysis of the number of pole teeth, the radial sealing gap height, permanent magnet thickness, slot width, the ratio of pole piece height to shaft and other key parameters on the magnetic fluid sealing performance. Finally, the reliability of the reciprocating magnetic fluid sealing withstand voltage is verified by experimental methods. Research indicates. The pressure capabilities of magnetic fluid sealing is increasing with the increase of the number of pole teeth. The pressure capabilities of magnetic fluid sealing is decreasing with the increase of the radial sealing gap. The sealing withstand voltage increases first and then decreases with the increase of the thickness of the permanent magnet, and finally increases, and the value of the withstand voltage is the largest when the thickness of the permanent magnet is 7.8 mm. The sealing pressure capabilities increases as the slot width increases. The sealing withstand voltage increases first and then decreases as the ratio of pole piece height to shaft increases, and when the ratio of pole piece height to shaft is 0.8, the sealing withstand voltage reaches a maximum value. The pressure test finally reaches the pressure value of 6 MPa, which can meet the pressure value demand of medium pressure cylinder, indicating that the magnetic fluid sealing technology can effectively solve the leakage problem existing in the air cylinder technology of Aerospace Engineering, and improve the reliability and service life of the air cylinder.

Description: In order to study the effect of the trailing edge sweep angle of the centrifugal impeller on the aerodynamic performance of the centrifugal compressor, 6 groups of centrifugal impellers with different bending angles and 5 groups of different inclination angles were designed to achieve different impeller blade trailing edge angle. The computational fluid dynamics (CFD) method was used to simulate and analyze the flow field of centrifugal compressors with different blade shapes under design conditions. The research results show that for transonic micro centrifugal compressors, changing the blade trailing edge sweep angle can improve the compressor’s isentropic efficiency and pressure ratio. The pressure ratio of the compressor shows a trend of increasing first and then decreasing with the increase of the blade bending angle. When the blade bending angle is 45°, the pressure ratio of the centrifugal compressor reaches a maximum of 1.69, and the isentropic efficiency is 67.3%. But changing the inclination angle of the blade trailing edge has little effect on the isentropic efficiency and pressure ratio. The sweep angle of blade trailing edge is an effective method to improve its isentropic efficiency and pressure ratio. This analysis method provides a reference for the rational selection of the blade trailing edge angle, and provides a reference for the design of micro centrifugal compressors under high Reynolds numbers.

Description: A new core vibration calculation method of UHV shunt reactors is proposed to deal with the problem that vibration parameters of the core of an ultra-high voltage (UHV) shunt reactor cannot be measured on site. A series of tests have validated that the method can calculate the vibration parameters of a UHV shunt reactor core with different voltage ratios. The method is adopted to study the influence of nodal voltage fluctuations of the UHV AC tie line on the core vibration characteristics of a UHV shunt reactor under normal and abnormal operating conditions. The conclusion is drawn as follows: in the three operating states assessed herein, no matter whether the power grid is in a normal state or not, the core of the UHV shunt reactor will not reach magnetic saturation, and the vibration parameters of the reactor always maintain a linear relationship with the operating voltage. The changes of power grid operation parameters are introduced to the research into reactor vibration, which is conducive to a more comprehensive understanding of the actual operating state of a UHV shunt reactor. It can also provide help for the design and operation of UHV shunt reactors.

Description: In this paper, a magnetorheological (MR) damper with multiple axial fluid flow channels is developed to solve the conflicts between limitation of size dimension and improvement of damping performance. By setting symmetrical excitation coils at both ends of the MR damper, the effective fluid flow channels of the proposed MR damper are significantly lengthened. In order to investigate the distributions of magnetic flux lines and magnetic flux density of the MR damper, the finite element model of the MR damper is established by using ANSYS software. Moreover, an optimization method combining BP neural network and particle swarm optimization (PSO) is proposed to improve the magnetic field utilization of the designed damper, and the damping performances of initial and optimal MR dampers are also experimentally tested. The test results show that the output damping force of initial and optimal MR dampers is 3.13 kN and 5.98 kN respectively under the applied current of 1.8 A, increasing by 91.1%, and the dynamic adjustable range is 11.5 and 16.1 respectively, increasing by 40.0%. It is found that the damping performance of the proposed MR damper is significantly improved.

Description: This paper presents a multi-material topology optimization for the design of permanent magnet synchronous motors (PMSMs). Specifically, structural shapes of permanent magnet (PM) and iron core in a PMSM rotor are simultaneously designed together with the orientation of PM magnetization. For a co-design of PM and iron core, relative permeability and residual magnetic flux density are interpolated by the three-field density approach based on the Helmholtz filtering and regularized Heaviside step function. Here, the Helmholtz filtering aims to attain smooth border in design results, and the Heaviside function enables us to acquire a clear border (i.e. zero-one design) without intermediate densities. The optimization goal is set as maximizing the average torque of PMSMs. The average torque is calculated by Maxwell stress tensor (MST) method considering a maximum torque per ampere (MTPA) control. To validate the effectiveness of the proposed multi-material topology optimization approach, a PMSM rotor with 4 poles and 12 slots is designed. In addition, design results at various settings of input current amplitude and PM strength are compared and discussed. When the input current is stronger than the PM strength, rotor PM and iron core are designed for utilizing both PM and reluctance torque components like V-shape interior PMSMs. On the other hand, in the case of stronger PM strength, PM is designed near the air-gap, which utilizes only PM torque component like surface PMSMs.

Description: To reveal the flame propagation and CO/CO2 generation characteristics of coal dust explosion, lignite dust cloud is studied through experiment and numerical simulation in a horizontal pipeline apparatus. The result indicated that within 0.5 s after explosion, the flame propagation distance rapidly increases until the explosion reaction is sufficient. FLUENT is used to simulate the flame propagation and CO/CO2 generation characteristics. It is found that the simulation error is acceptable and the simulation result is consistent with the experimental result. The explosion space is divided into five zones by simulating the flame temperature. It also revealed that z = 0.3 ~ 0.6 m in the pipeline generates more CO because it is closed to the ignition zone. As the explosion spreads through the pipeline, the generated CO accumulates to the bottom of the pipeline, and the generated CO2 accumulates more in the upper part of the pipeline.

Description: In city gas pressure reducing stations, in order not to hydrate natural gas after a sudden drop in pressure, the gas temperature is raised by a heater. The increase in temperature is such that after the pressure drop, the gas inside the pipes does not freeze. These heaters are gas burning and very high consumption, and because they use fossil fuels, produce environmental pollution. Accordingly, in this research, solar energy will be used to preheat the gas, which will be used for the most accurate analysis of TRNSYS software. In this regard, the amount of utilization of the sun and the amount of energy required for preheating will be obtained. After the implementation of the TRNSYS program, the highest amount of energy supply by the sun is related to spring, which on this day provides 55% of the thermal energy required by the load by solar energy.

Description: In order to reduce the carbon emission and improve the de-carbonization in distribution of vehicle routing problem with simultaneous delivery and pickup (VRPSDP), a two-stage disruption management method based on the changes of customer demand is proposed in this paper. Firstly, a mathematics model of VRPSDP is established to optimize the parameters and the distribution carbon emission cost and time window deviation. Next, several carbon emission equations in VRPSDP are inducted and designed. Considering the strong global searching ability of quantum particle swarm optimization (QPSO) and combing the advantages of superposition and parallelism of quantum computing, a multi-phase QPSO (MQPSO) is proposed to enhance global searching ability. At last, on the basis of Solomon examples, the validity of the proposed model and MQPSO is tested and compared with the classical algorithms at present. The simulation results show that the proposed method can not only achieve the goal of performance but also meet the practical requirements of reducing carbon emissions in VRPSDP.

Description: Renewable energy sources cannot guarantee long-term and stable output supply when they are given energy consumption at the load end. At the same time, traditional solar and utility power supply systems cannot guarantee the priority of using solar energy to generate electricity, which has certain limitations. In this regard, an energy control strategy for achieving smooth and no backflow switching and prioritizing the use of clean energy solar energy under a joint power supply system of a solar power grid and a municipal power grid is proposed, which is used for a conventional combined power supply system of a contactor switching circuit. A topology of low voltage power grid is proposed, which effectively reduces the impact on the solar power grid and the municipal power grid during the system switching process combined control mode for controlling the current phase and repetitive control at the output end of the solar power grid in the combined power supply mode, and adding a feedforward control method for the grid voltage is adopted to ensure that the solar grid and the municipal power prioritize the use of clean energy solar energy and, at the same time, ensure the maximum utilization of solar energy. This paper chose the combined power supply system with the solar power grid and the municipal power grid as the object of this research. The topology structure and controlling strategy of the power supply system were comprehensively and deeply researched, and on this basis, the combined power supply system prototype was designed on the foundation of DSP28335 and CPLD. Moreover, hardware parameters are designed in the system, and an energy management optimization algorithm based on the system is developed on the corresponding experimental platform. The experimental results show that the proposed energy control strategy can effectively reduce the impact on the solar power grid and the municipal power grid during the system switching process, ensure that the solar power grid and the municipal power grid have no backflow combined power supply and give priority to the use of clean energy solar energy.

Description: The present investigation analyzes the influence of Cattaneo–Christov heat and mass fluxes on peristaltic transport of an incompressible flow. The fluid is obeying Bingham alumina nanofluid. The fluid flows between two co-axial vertical tubes. The system is expressed by a varying radially magnetic field with respect to the space. Soret effect and non-Darcy porous medium are taken into account. The governing system of equations is tackled by utilizing the approximations of long wavelength with low Reynolds number and with the help of homotopy perturbation method (HPM). It is noticed that the axial velocity magnifies with an increase in the value of Bingham parameter. Meanwhile, the value of the axial velocity reduces with the elevation in the value of the magnetic field parameter. On the other hand, the elevation in the value of thermal relaxation time leads to a reduction in the value of fluid temperature. Furthermore, increasing in the value of mass relaxation time parameter makes an enhancement in the value of nanoparticles concentration. It is noticed also that the size of the trapped bolus enhances with the increment in the value of Bingham parameter. The current study has many accomplishments in several scientific areas like medical industry, medicine, and others. Therefore, it represents the depiction of the gastric juice motion in the small intestine when an endoscope is inserted through it.

Description: High speed photography by Caustics method using Cranz–Schardin camera was used to study crack propagation and divergence in thermally tempered glass. Tempered 10 mm thick glass plates were used as a specimen. New crack generation by two crack collision was observed. Regarding the presence/absence of new cracks, the dependence of the two cracks on the collision angle was confirmed. Considering that it is based on the synthesis of stress ?CR generated at the crack tip, tensile stress necessary for the generation of new cracks could be created.

Description: BACKGROUND: A rolling bearing bush alloy of a feed water pump that is part of a waste heat boiler of an oil refinery has failed. OBJECTIVE: We try to analyze the reasons that caused the working surface of the bearing bush of the water pump to fall off and then give some suggestions to this failure. METHODS: The composition, microstructure, pit, and crack morphology of the bearing bush alloy were analyzed by the X-ray fluorescent analysis, the energy spectrum analysis, the optical microscope and the scanning electron microscope, respectively. RESULTS: The content of Pb in the bearing bush alloy was high, and the Cu content was low. The primary crystal Cu6Sn5 was low, and the crystal of SnSb with low density moved upward and segregated. The above phenomenon reduced the fatigue resistance of the babbitt alloy. The bearing bush was subjected to alternating loads in service, and several small cracks were generated on the bearing bush alloy working surface. The cracks continued to expand and connected with each other. Fatigue pitting occurred on the bearing bush working surface, a large number of pits were formed, and several large alloy blocks fell off. CONCLUSIONS: The Pb content in the failed bearing bush alloy was too high and did not meet the requirements of the Sn-based babbitt alloys in the national standard. At the same time, the primary crystal Cu6Sn5 formed by Cu and Sn was low due to the low Cu content, and the crystal SnSb with a small density moved upward and segregated. The composition of the babbitt alloy, especially the Cu content, should be strictly controlled to ensure the safe and reliable operation of the bearing.

Description: For precision engineering, a linear PM-moving actuator with trapezoidal PMs and trapezoidal coils considering the fringing effect is proposed. To take into account the effect of the finite-long trapezoidal PM array, an improved Fourier series expansion is developed to calculate the fringing-included magnetic field. Then the full-stroke thrust excited by the trapezoidal coils is accurately predicted and validated by the finite element method. Sensitivity of the trapezoidal parameters of PMs and coils is analyzed, and combined optimization is implemented by the genetic algorithm. Through the Pareto optimal solutions of thrust, the relation of the PM-coil parameter combination is described and formulated by curve fitting. Compared with the traditional rectangular PM actuators or other trapezoidal-typed actuators, the proposed actuator with trapezoidal PMs and coils further decreases the thrust ripple and largely increases the thrust magnitude simultaneously, and reaches an utmost-close effective stroke as well.

Description: Crack orientation is a vital factor in the behavioral study of fractures, especially the study of crack propagation in structures that are under dynamic or fatigue loading. Indeed, many non-destructive testing (NDT) techniques have been developed recently for the detection of cracks such as the eddy current testing (ECT). However, the crack orientation has not been undertaken into consideration. In this paper, a NDT based on eddy current using 3D finite element modeling, is proposed for the determination of the crack orientation. The idea of this proposed technique benefits from the influences of crack orientation, which can be observed on the components of eddy current and the related magnetic flux density following the x, y axes, for the estimation of the crack angle orientation based on an interpolation criteria. The obtained results through the presented simulation prove the validity of the proposed technique for the detection of crack angle orientation.

Description: An electrically thin (0.024?0) high-impedance surface (HIS) on a magneto-dielectric nanocomposite (NC) is presented as an external shield for wideband absorption of mobile phone radiation. Characterization of the NC and numerical design and analysis of the miniaturized HIS unit cell on NC (0.088?0 × 0.088?0) are presented over 0.85–6 GHz, where ?0 is the free space wavelength at the absorber resonant frequency. The absorber performance is assessed using a mobile phone handset at 0.9 and 1.8 GHz Global System for Mobile Communications (GSM) frequencies and 2.4 GHz Wireless Fidelity (WiFi) frequency. Handset specific absorption rate (SAR) measurements with the absorber recorded in head phantom indicated 83, 48 and 71% reduction in peak SAR at 0.9, 1.8 and 2.4 GHz, respectively without significantly affecting the handset radiation characteristics in free space. Simulation results of human head model with the hand showed SAR reduction of 69, 24 and 65% at 0.9, 1.8 and 2.4 GHz, respectively for 1 g SAR. It is concluded that the proposed absorber could be used to lower handset SAR levels and shield mobile communication signals over 0.85–6 GHz.

Description: Magnetic targeted drug delivery systems can improve drug utilization and reduce drug side effects. There are still many difficulties to be overcome in clinical practice. The main problems include providing large enough magnetic capture particles to concentrate drug-loaded magnetic micro-nanoparticles (MNPs) to the lesion site. The existing research focuses on the development of targeted carriers, and the magnet device has not formed a mature research system. Based on the recent development of magnet devices in recent years, this paper proposes the research direction of potential magnet devices. From the dynamic behavior of the particles under the magnetic field, the magnetic system and the mathematical model design direction of the optimized magnet are developed. This article describes the obstacles encountered in drug targeting in the study of magnet devices and summarizes the potential development of future magnet devices.

Description: BACKGROUND: The analysis of seismic stability of structure is important in the field of engineering. OBJECTIVE: This study aims to verify the reliability of numerical simulation in seismic stability of reinforced concrete (RC) frame structure. METHODS: Based on the numerical simulation, the material constitutive model of RC frame structure was introduced and then a finite element model was established through ABAQUS to analyze its seismic stability. RESULTS: The simulation results of ABAQUS were similar to the test values, the tangent slope of the skeleton curve of the structure decreased gradually, the interstorey displacement of storey 1 was the largest, the maximum error of the interstorey displacement angle was 0.005, and the ductility coefficient was 4. CONCLUSIONS: The experimental results verify the reliability of the numerical simulation method and provide some theoretical support for its better application in the study of seismic stability.

Description: This paper reports the demonstration of design and implementation of narrow band band-stop filters using slotted ground resonators. Using coupled-mode resonator theory, the systematic implementation of BSFs are performed to achieve narrow stopband (

Description: The significance of post-disaster temporary housing for the victims has led to the problem of designing a good model of temporary housing. According to research hypothesis, using the design of Iranian nomads’ housing instead of common forms of temporary housing contributes to energy saving. Investigating the architecture of nomads’ housing indicates that there is a type of indigenous knowledge for designing and constructing this type of housing. After the study, data collection and a review of the types of Iranian nomads’ housing using library and causal method, thermal simulation was conducted to investigate the effect of changing the temporary housing form inspired by the nomads’ housing on energy consumption. Findings showed that using shapes like Kapars of Baluchistan nomads, wigwams of Shahsavan tribe in Ardabil and mudhifs of Khuzestan will save energy for 36%, 24% and 25%, respectively.

Description: The quality and shelf-life of NCS (non-centrifugal sugar) mainly depend on the moisture content present in it. NCS formed by the current practice of open sun drying contains moisture substantially greater than the acceptable level of 3%. This paper presents the work undertaken to design a tunnel dryer to achieve the required moisture content of granular NCS for various load conditions. An experimental investigation was conducted on a laboratory-scale dryer to achieve the required moisture content for various loads. This experimental data was compared with the output of two drying models and a validated one that could be used to design an industrial-scale dryer. For various load conditions on each tray and dryer exit temperature, nine different cases were determined. The number of trucks, drying time, and energy requirements were computed using the validated theoretical model. A tunnel dryer with a length, height and width of 18, 1.2 and 1 m respectively and 18 trucks with 24 trays on each truck is shown to be dry 1 tone of NCS based on the minimum energy requirement of 176.49 MJ, and a drying time of 68 min.

Description: 4-Amino-3-(2-bromo-5-methoxyphenyl)-1H-1,2,4-triazole-5(4H)-thione (ATH) was synthesized and characterized by nuclear magnetic resonance and Fourier-transform infrared as spectroscopical techniques and elemental analysis. ATH was studied for corrosion inhibition of mild steel in corrosive environment by means of weight loss technique, scanning electron microscopy and the adsorption isotherm. ATH demonstrates a superior inhibition efficiency against corrosion of mild steel. Adsorption data fit well to a Langmuir isotherm model.

Description: Hydrogen-fueled combustion systems are becoming popular in recent years. Methane is one of the significant hydrogen supplier in nature. Thus, in the study, the natural gas-fueled reactor-assisted solid oxide fuel-cell system is configured to provide a current to load the battery to turn the propeller of an unmanned aerial vehicle in the large-scale hydrogen-onboard system. The methane-fueled reactor has not been studied under a large-scale case in literature yet. To investigate the amount of products, this paper presents about the steam-reforming performance of natural gas in steady state and transient in the reactor. The influence of vital parameters such as steam/carbon, gas feed temperatures, the amount of heat transferred to the reactor in methane steam reforming for a plug flow reactor, and a continuous stirred tank-type reactor is investigated respectively. Methane conversion, yield of hydrogen gas and H2 gas generation for different medium conditions along the reactor are studied on by using the COMSOL Multiphysics program. The steady-state and time-dependent characteristics of the steam reforming of natural gas are focused on. The high conversion ratio of methane gas is obtained by ranking the steam/carbon ratio. The released hydrogen gas molar flow rate is increasing according to the reactor volume. The achieved power provided by produced gas of H2 is 97 hp supplying the thrust force for an unmanned aerial vehicle.

Description: The corrosion inhibition of Schiff base, namely 2-((2-hydroxy-5-methoxybenzylidene)amino)pyridine (HMAP), for mild steel (MS) in a 1 M hydrochloric acid environment was investigated by means of weight loss and scanning electron microscopy techniques. Quantum chemical calculation based on density functional theory (DFT) was carried out on HMAP. Results illustrated that HMAP is a superior inhibitor for the corrosion of MS in 1.0M hydrochloric acid environment, and inhibition efficiency is higher than 90.0% at 0.5 g/L HMAP. Inhibition performance increases with regard to concentration increase and inhibition performance decreases when raising temperature. Adsorption of the inhibitor on the MS surface followed Langmuir adsorption isotherm and the value of the free energy of adsorption; ΔGads indicated that the adsorption of HMAP was a physisorption/chemisorption process. The DFT refers to perfect correlation with methodological inhibition performance.

Description: Ecological footprint (EF) is an indicator that accounts for human demand in the environment compared with the sizes of the bio-productive land and sea areas. This research was carried out to determine the EF for environmental sustainability in Ilorin Metropolis. Empirical surveying, which involved systematic random sample technique, was used to select residential households in each community for this investigation. The EF indicators, which include food, energy and waste consumptions, were determined empirically. The bio-capacity (BC), ecological stress and deficit were determined, from the land used as environmental sustainable areas in Ilorin, using Google Earth Mapping. The results revealed that energy has the highest EF of 44%, followed by waste and food with the footprint of 25% and 5%, respectively. A deficit of 38% was obtained, and this requires eight times the BC to balance the EF of the population. This implies that people are consuming more of the energy and generating more wastes than they consumed food.

Description: The case study presented in this paper is an innovative ground source heat pump (GSHP) system constituted by a hybrid Photovoltaic Thermal (PVT) solar system for poultry houses. Farmers tend to not to apply GSHPs because of the high prices of excavation and time consumption. The innovative heat pump system assessed in this study comprises of a new type of heat exchangers; a thin-tube solar polyethylene heat exchanger installed between roof tiles and PV panels and a novel vertical ground heat exchanger to utilize the heat stored in the soil. The heating system applied to a poultry house are monitored and evaluated under a variety of environmental and operating conditions to achieve annual/long-term efficiency of the heating system in Kirton, UK. The maximum heating demand of the poultry house is determined 34.4 MWh/PC while the minimum is 11,1 MWh/PC. The monitored results show that the heat pump produced 15.02 MWh of thermal energy per annum. Solar PV and heat pump worked very well together with solar PV covering all the heat pump’s annual electrical energy requirement and generated 8.74 MWh of extra electricity exported to the grid. The seasonal coefficient of performance is found 3.73 through a year. The novel PVT-GSHP heating system is a very promising solution for high fossil fuel consumption in the agriculture industry and the energy savings of the whole system can be noticeably increased dependent up on the system controlling.

Description: This paper introduces an innovative thin film PV vacuum glazing (PV-VG) technology. In addition to electricity generation, the PV-VG glazing can also reduce heat loss from the building in winter and reduce heat gain in summer. In building integrated photovoltaics application, optical characterization of the PV glazing is important in determining the solar ray transmission and thermal transfer process of the glazing. This paper discusses the optical properties of the PV-VG glazing by considering the different layers of the glazing unit that includes a self-cleaning glass, a thin film PV glass and a low-e vacuum glazing. Based on the optical transfer matrix, the transmission coefficients of different film layers were deduced. The theoretical calculations were then validated against the transmission coefficient experiment of the PV-VG using an EDTM SS2450 Solar Spectrum Meter. The calculation error of the transmission coefficient of the single-layer glazing is generally within 5%, the calculation error of the transmission coefficient of the integrated PV-VG glazing is about 6%. The results show that the average visible light transmission coefficient, the average infrared light transmission coefficient and the overall transmission coefficient of PV-VG glazing are 19%, 16% and 12%, respectively. The study is important to optimize the visible light transmission of the PV-VG glazing; the optical model obtained above lays a solid foundation for further study of transmission coefficient analysis of different functional coating of PV-VG glazing.

Description: Renewable energy technologies have been developed in recent years due to the limited sources of fossil fuels, the possibility of depletion of fossil fuels and the related environmental issues. In these types of systems, it is crucial to reach optimum sizing in order to have an affordable system based on solar and wind energy and energy storage. In this study, a powerful optimization scheme based on tabu search, called discrete tabu search, has been proposed for sizing three stand-alone solar/wind/energy storage (battery) hybrid systems. For validating the applied algorithm effectiveness, the results are compared with the results found by the discrete harmony search. The obtained outcomes are compared on the basis of total annual cost. The components of the scheme are analyzed in different operating conditions by applying meteorological data in addition to real time information from three typical regions of Iran. According to the obtained data, applying ‘discrete tabu search’ leads to better outputs on the basis of mean, standard deviation and worst indexes.

Description: Based on 804 samples of farmers in Hubei Province, a typical major grain-producing area in China, this study empirically analyzed the effects of two different policy tools, i.e. economic incentives (subsidies) and order enforcements (regulatory restrictions), as well as the effects of their interaction, on farmers’ chemical fertilizer reduction and substitution behaviors. Samples were grouped according to the degree of concurrent employment to analyze the effects on different groups. The results show that (1) the influences of these policies on the behaviors were significantly positive; (2) after constructing the interactive variables of the policies, the influence of the order enforcement policy was no longer significant, but the influence of the interaction was significantly positive; (3) the low-degree concurrent employment farmers were more likely to be affected by the order enforcement policy, whereas the high-degree ones were more affected by the economic incentive policy; and (4) the behaviors of the low-degree ones were strongly affected by family management characteristics, whereas the high-degree ones were more affected by the farmers’ individual characteristics.

Description: The present study aims to investigate the thermodynamic and financial aspect of concentrated solar power (CSP) plant hybridized with biomass-based organic Rankine cycle (ORC), thermal energy storage (TES), hot springs and CO2 capture systems. The organic working fluids namely R123, R235fa, D4 and MDM are selected for designing the hybrid system at different operating conditions. The nominal power capacities of the CSP and biomass ORC plants are 1.3 MW and 730 kW respectively. Additionally, a parametric study has been carried out to understand the influencing parameters that affect the system’s performance. From the results, it is revealed that the biomass ORC plant with a hot spring system alone can develop a power of 720 and 640 kW for D4 and MDM respectively. Furthermore, the power generation can be increased with addition of TES in the CSP plant. From the economic point of view, the hybrid system with special focus on CO2 capture could be very profitable if the levelized cost of electricity (LCOE) is fixed at 0.24$/kWh. In this scenario, the payback period is 8 years with an internal rate of return (IRR) more than 8%. Therefore, the hybrid system is thermodynamically and financially attractive for dispatchable electricity.

Description: Geothermal energy is a kind of green and non-polluting renewable energy. Medium and low-temperature geothermal energy below 150 °C is usually used directly for heating, industrial and agricultural heating, bathing, etc., and the utilization rate is low. Organic Rankine cycle (ORC) system can be used in a low-temperature geothermal power generation systems. Thermodynamic analysis of the thermal cycle system is carried out in this paper. Based on the principle of exergy analysis, the cycle parameters such as evaporation temperature, condensation temperature, superheating temperature, and supercooling temperature are analyzed. The results show that the exergy efficiency and system output power can improve by increasing evaporation temperature and the exergy loss can decrease in the evaporator. Increasing superheating temperature enhances the output power of the expander and the exergy loss in the condenser, decreases the exergy efficiency simultaneously. Increasing condensation temperature decreases the exergy efficiency of the system and the output power of the expander, and increases the exergy loss of the system. Although the output power of the expander will not be affected by supercooling temperature, the rise of supercooling temperature will reduce the exergy efficiency of the system and increase the exergy loss of the evaporator.

Description: The present work aimed to select the optimum solar tracking mode for parabolic trough concentrating collectors using numerical simulation. The current work involved: (1) the calculation of daily solar radiation on the Earth’s surface, (2) the comparison of annual direct solar radiation received under different tracking modes and (3) the determination of optimum tilt angle for the north-south tilt tracking mode. It was found that the order of solar radiation received in Shanghai under the available tracking modes was: dual-axis tracking 〉 north-south Earth’s axis tracking 〉 north-south tilt tracking (β = 15°) 〉 north-south tilt tracking (β = 45) 〉 north-south horizontal tracking 〉 east-west horizontal tracking. Single-axis solar tracking modes feature simple structures and low cost. This study also found that the solar radiation received under the north-south tilt tracking mode was higher than that of the north-south Earth’s axis tracking mode in 7 out of 12 months. Therefore, the north-south tilt tracking mode was studied separately to determine the corresponding optimum tilt angles in Haikou, Lhasa, Shanghai, Beijing and Hohhot, respectively, which were shown as follows: 18.81°, 27.29°, 28.67°, 36.21° and 37.97°.

Description: Renewable energies could be a good solution to the problems associated with fossil fuels. The storage of wind energy by means of small-scale devices rather than large-scale turbines is a topic that has gained lots of interest. In this study, a compact device is proposed to harvest wind energy and transform it into electrical energy, by means of oscillations of a magnet into a coil, using the concept of vortex-induced vibration (VIV) behind a barrier. For a more comprehensive investigation, this system is studied from two viewpoints of fluid mechanics (without magnet) and power generation (with the magnet). For this purpose, an oscillating plate hinging on one side and three barriers with different geometrical shapes including cylindrical, triangular and rectangular barriers are used. In addition to the effect of barrier geometry, the impacts of various barriers dimensions, the distance between the plate and the barriers as well as inclination angle of the plate with respect to the horizon on the amplitude of oscillations and generated power are investigated. Results showed that in each case, there is a unique Reynolds number in which the frequency of vortex shedding equals to the frequency of plate oscillation and the output power from the energy harvester device is maximum. Besides, by increasing the barrier dimensions, the amplitude of oscillations increases up to three times, which leads to a higher generated power. Finally, by considering the studied parameters, the best conditions for generating energy using the VIV method are presented for design purposes. Among all the considered cases, the cylindrical barrier with the highest diameter and nearest distance to the plate led to the highest efficiency (0.21%) in comparison with other barriers.

Description: In this study, thermodynamic analysis was performed on basic and recuperative transcritical organic Rankine cycles by using five pure and six mixed fluids. The effects of evaporation parameters on the first- and second-law efficiencies (ηI and ηII) as well as power output were investigated. The results indicate that a recuperator had a positive effect on the ηI and ηII and negative effects on the specific power. The total irreversibility of the system was improved by the recuperator. However, the total irreversibility considerably increased with an increase in the expander inlet temperature (Texp,in) due to the significant increase in irreversibility in the condenser, particularly for working fluids with low critical temperatures, namely R134a, R1234yf and R290, and low proportions of R245fa and R600a in mixed fluids. For both the pure and mixed fluids, the specific power linearly increased with an increase in the expander inlet pressure (Pexp,in) and Texp,in. However, with an increase in Pexp,in, the ηI and ηII first increased and then decreased. Finally, for ηI and ηII, the effect of the recuperator increased with an increase in Texp,in even though the recuperator had a relatively small effect on the working fluids with high critical temperature, especially when Pexp,in was high.

Description: In this work, the network data envelopment analysis (DEA) model was used to divide the transformation of scientific and technological achievements in colleges and universities into two stages, which makes up for the lack of process measurement in a single DEA model. Also, the relationship between the transformation efficiency of scientific and technological achievements in universities and the development of a low-carbon economy was quantitatively analyzed. The research results show that: (1) the transformation efficiency of scientific and technological achievements of universities in China is increasing year by year and which is significantly higher in the eastern region than that in the central and western regions. (2) The efficiency of the transformation of scientific and technological achievements of the university promotes the reduction of carbon emission intensity and the development of a low-carbon economy, indicating that the improvement of the transformation efficiency of scientific and technological achievements of the university has a good role in promoting the ecological environment protection. However, compared with the developed countries, the quantity and quality of science and technology supply and ecological environment protection in China’s universities are still insufficient. In this regard, the development suggestions are put forward from the aspects of government policy guidance, professional talent cooperation and strengthening the docking between universities and industrial low-carbon economic development. The purpose of this paper is to promote the development of a low-carbon economy by improving the efficiency of scientific and technological achievements transformation in universities, to achieve the goal of ecological environment protection.

Description: In order to improve the friendliness of the grid connection of new energy power generation, the new energy photovoltaic (PV) unit is equivalent to a synchronous generator in the power system and a virtual synchronous generator (VSG)-controlled PV energy storage complementary grid-connected power generation system model is established and studied to analyze the VSG. When power is supplied to the load together with the power grid, the energy storage unit inside the VSG will release and store the electrical energy according to the fluctuation of the PV output, which plays the role of the adjustment of the prime mover; in the case of load power fluctuations, and power grid assume the corresponding active power regulation according to their capacity. The amount of active power adjustment to jointly and maintain the power balance inside the system under the condition of fluctuating load power. The overall system architecture and control strategy of PV grid-connected inverter based on VSG algorithm are proposed. The PV-VSG proposed here not only takes into account the maximum power point tracking control but also has independent participation in the power supply. A series of characteristics of synchronous generators, such as network frequency modulation voltage regulation and inertia damping, can effectively improve the new energy PV power generation system and promote the new energy consumption. The results of system simulation and field demonstration operation fully show the effectiveness and correctness of the proposed control strategy based on VSG algorithm.

Description: A roof-mounted radiant cooling system incorporating a bypass structure, intended for use on liquid natural gas (LNG)-fueled refrigerated vehicles and offering stable dynamic regulation was designed. A model was established using the TRNSYS software package to simulate the operation of this system, and the effects of various factors on the refrigeration performance were analyzed. The quantitative relationship between the LNG flow rate and the ambient temperature was determined and a dynamic regulation strategy proposed. The results of this work show that, when the vehicle is operated at an economical speed, the cooling capacity provided by the system is greater than 1.2 kW, which meets the requirements for a refrigerated vehicle. The dynamic regulation approach developed in this study was found to allow use of the refrigerated vehicle under different climactic conditions and to improve the stability of the cooling system.

Description: The increasing global energy and environmental problems are encouraging to the development and utilization of renewable and clean energy in various countries. Wind power is one of the major source in large-scale renewable energy applications. However, the frequency regulation becomes a critical issue while the technology is spreading. Research on the frequency modulation (FM) technology of wind turbines and its control strategy for future power grids become significant. The paper proposes a novel coordinated frequency control strategy with the synchronous generator to solve the unmatched state between the output power of the doubly-fed wind turbines (doubly-fed induction generators) and the grid frequency, combined with the frequency response characteristics of the synchronous generator. The FM coordination strategy is formulated by the modulation coefficient from current wind speed and operation mode of each wind turbine. By coordinating the FM output of the doubly-fed wind turbine and the synchronous generator within the allowable range of frequency deviation, it will achieve the dual goal of reducing the frequency regulation pressure of the synchronous generator and indirectly reducing the abandoned wind volume of the wind turbine. The simulation is carried out on the MATLAB/SIMULINK platform. The results show that the presenting variable coefficient frequency modulation strategy could significant smooth the wind power fluctuation, and allow the reserve power of the doubly-fed wind turbine can fully engaged in frequency modulation which will reduces the frequency modulation pressure of the synchronous generator in the system.

Description: The moisture extraction rate (MER) and energy efficiency of domestic gas clothes dryers, heat-pump clothes dryers and electric clothes dryers were assessed. The assessment was performed with regard to five indices: the MER, specific MER, specific thermal energy consumption for dehumidification (mSPC), energy efficiency (ηt) and primary energy efficiency (η1). The effects of the dry mass of clothes (mBD) and the ambient temperature on the performance of the clothes dryers were evaluated. The experiments were divided into two parts. In the first part, the ambient temperature was 20°C, and mBD was set as 1.5, 2.5, 3.5, 4.5 and 6 kg. In the second part, mBD was 3.5 kg, and the performance of the dryers was tested at ambient temperatures of 5, 7.5, 10, 12.5, 15 and 20°C. The experimental results indicated that the gas dryer had the highest MER the heat-pump dryer had the best performance with regard to energy conservation and all three types of dryers had a higher MER and energy efficiency when the ambient temperature increased. The performance of the gas dryer was lower than that of heat-pump dryer when the temperature was 20°C. But when the temperature was

Description: In the current work, the influences of titanium oxide (TO) on nanocomposites using epoxy (EP) resin have been investigated. EP resin was added to various contents in terms of volume of TO (6%). Based on the casting method, the TO-EP nanocomposites were prepared. Mechanical properties in terms of tensile, impact and hardness properties exhibited improvements in the mechanical results of the TO-EP nanocomposites. The experimental results exhibited that the enhancement in the tensile strength, impact, and hardness was found to be 14 MPa, 40.1 J/mm2 and 228.9 HV, respectively. Moreover, the effect of the strength has decreased compared with pointing to brittleness that increased the TO-EP nanocomposites. Field emission scanning electron microscopy (FESEM) analysis was used to perform a microstructure analysis which in turn revealed how TO obstruction the cracks propagation in the nanocomposites. The interface between the TO and the EP nanocomposites was observed using the FESEM images. The results highlighted that the TO-EP nanocomposites can be used a wide range of industrial applications such as biomedical application.

Description: Hotels hold an important role in the energy efficiency policies of the European Union (EU), as they are typically ranked among the top energy consumers in the non-residential sector. However, a significant amount of the energy used in hotels is wasted, leaving ample room for enhancing energy-efficiency and resource conservation. Indeed, energy refurbishment of the hotel building stock is crucial in order to reach the nearly zero energy building (nZEB) status imposed by EU Directives for energy efficiency, and also an important pillar to achieve the energy targets for 2030 and the transition towards climate-neutral levels by 2050. A typical 4-star hotel in operation in Faro (Portugal) was used as a case study in order to establish energy performance indicators for nZEB hotels in three European cities, taking into account the influence of the climatic context, the technical feasibility and cost effectiveness of the best energy retrofit packages. The study started after the calibration of the building energy model by means of an energy audit and measured data, in order to have a baseline model that represents well the actual energy use of the hotel in the reference location. The building energy model was developed by using DesignBuilder/EnergyPlus software. The validated model was then used to assess the effect of the best retrofit interventions (energy efficiency measures and active solar systems) in order to set minimum energy performance requirements and to reach cost-optimal levels and nZEB levels for refurbished hotels. A significant energy-saving potential was found for the cost-optimal benchmarks, and the obtained nZEB levels can be achieved under technically and economically conditions for the selected cities: Faro, London and Athens.

Description: Prefabricated buildings constructed to be used in a specific region cannot be assumed to work unconditionally in different climates around the world. It is important to develop passive house solutions for each location, suitable for the actual climate and geographic conditions. Shelters could be used in different applications such as refugee housing or telecommunication stations. Photovoltaic energy could cover the electricity consumption of these shelters. Shelters for different applications should be usable in all weather conditions, and because of that different climate zones were chosen. A full study about three climate zones was done to study the different factors that play a significant rule in choosing the location of the shelter. In this study, prefabricated housing was designed to ensure thermal comfort by doing structure design changes and using solar energy as an energy source. Three different locations have been chosen to be able to perform the best structure and components design for every location, taking into consideration the assumptions taken in each place. The total photovoltaic system was designed with a capacity of hot, moderate and cold climate zones with 2.0, 1.8 and 3.45 kWp, respectively, along with energy plus the production of 38% in the hot, 47% in the moderate and 28% in the cold climate.

Description: From the last few years, the use of efficient ejector in refrigeration systems has been paid a lot of attention. In this article a description of a refrigeration system that combines a basic vapor compression refrigeration cycle with an ejector cooling cycle is presented. A one-dimensional mathematical model is developed using the flow governing thermodynamic equations based on a constant area ejector flow model. The model includes effects of friction at the constant-area mixing chamber. The current model is based on the NIST-REFPROP database for refrigerant property calculations. The model has basically been used to determine the effect of the ejector geometry and operating conditions on the performance of the whole refrigeration system. The results show that the proposed model predicts ejector performance, entrainment ratio and the coefficient of performance of the system and their sensitivity to evaporating and generating temperature of the cascade refrigeration cycle. The simulated performance has been then compared with the available experimental data from the literature for validation.

Description: Cement-based materials have been widely used in bridge construction. In order to further improve their performance, this study analyzed the modification and optimization functions of nano-SiO2 materials, designed test specimens with different content of nano-SiO2 and conducted experiments on their flow performance, compression resistance, bending resistance and impermeability. The results showed that the flow performance of the materials decreased and the impermeability decreased with the increase of nano-SiO2 content. The compressive strength and flexural strength are the best when the content of nano-SiO2 is 1%. On the whole, the best content of nano-SiO2 is 1%; when the content of nano-SiO2 is 1%, all the properties of the specimens are good, which is more conducive to the construction of bridges in various complex environments. The research in this paper has made some contributions to the further application of nano-SiO2 in the optimization of building materials, which is conducive to the better development of building materials.

Description: As one of the most promising and convenient heating service to replace coal-fired boilers and electric heaters due to its high energy efficiency, a heat pump has received more and more attention for the economical application and extensive research. The injection technology can be used to improve the heat pump performance. Currently, the injection ratio and pressure ratio are usually used to characterize the effects of injection styles on its performance. This is not conducive to its practical operation control because of additional cost increase. In this work, the effects of two injection cycles due to two injection paths were characterized with openings of a sub-cooling electronic expansion valve, comparatively tested and analyzed. Test results demonstrate that the heating capacities (Qh), electricity power (EP) and coefficient of performance with the refrigerant injection into compressor (CRI) are more than those with the injection into accumulator (ARI), and the overall effect with the CRI is positive because the Qh improvement outperforms EP increase. For example, the maximum Qh with the CRI at 55, 60 and 85 rps were 8.1%, 7.7% and 18.3% higher than those without the CRI, and 7.3%, 6.7% and 19.0% higher than those with the ARI. The thermodynamic model was used to analyze the experimental results and expound the mechanism of the influence of injection path on the performance of heat pump. This work provides guidance for improving energy efficiency in common areas and enhancing Qh in cold areas.

Description: In order to reduce the cost of central air conditioning, we need to reduce its energy consumption. This paper briefly introduced Internet of Things and the energy-saving and comfort monitoring system of central air conditioning based on the Internet of Things. The system took comfort degree as constraint and energy efficiency as objective to control energy saving of central air conditioning. Company X in Guanghan, Sichuan, China, was taken as an example for analysis. The system was compared with the energy-saving control system which took temperature and power as constraints. Compared with before the energy-saving control, the proportion of air conditioning downtime in the working hours of employees increased after the implementation of the two kinds of energy-saving control systems, and the proportion of downtime under the energy-saving control system designed in this study was larger; in addition, after the control of the two kinds of energy-saving systems, the energy efficiency of the air conditioning significantly improved, and the air conditioning under the control of the energy-saving system proposed in this study had more improvement in energy efficiency and higher energy-saving efficiency. The energy-saving control method proposed in this study can effectively reduce the power consumption of the central air conditioning in the office.

Description: The effect of surface wettability on droplet impact on spherical surfaces is studied with the CLSVOF method. When the impact velocity is constant, with the increase in the contact angle (CA), the maximum spreading factor and time needed to reach the maximum spreading factor (tmax) both decrease; the liquid film is more prone to breakup and rebound. When CA is constant, with the impact velocity increasing, the maximum spreading factor increases while tmax decreases. With the curvature ratio increasing, the maximum spreading factor increases when CA is between 30 and 150°, while it decreases when CA ranges from 0 to 30°.

Description: The non-centrifugal sugar (NCS) industry is one of the oldest small-scale cottage industry in India, whose technological features are not changed for several decades due to which the production and consumption of NCS has reduced significantly. One way to attend this problem is to select the best and sustainable methods among the existing technologies at various stages in the production process. In the production of NCS, juice extraction is the primary and essential process. The present work gives an insight to a logical procedure for selecting a suitable and sustainable juice extraction method for improving the NCS production using multi-criteria evaluation (MCE) technique. The selection process is based on 11 evaluation criteria covering various sustainable factors viz. technological, economic and environmental factors. Fuzzy analytical hierarchical process (FAHP) integrated with elimination et choix traduisant la realité method is the MCE technique considered for selecting the most appropriate crushing method among five alternatives. The results indicated that the power-operated single horizontal crusher is the most suitable and sustainable crushing method for improving the production rate of NCS. The same technique can be used for the other process unit of the NCS production to improve the productivity and sustainability of NCS.

Description: The concept of green buildings has recently arisen in order to contribute to solving some environmental, energy and economic issues. To meet the green building requirements, this paper describes an integrated design approach to improve the energy and water efficiency of the mid-rise residential buildings in Jordan using the eQUEST energy simulation tool. The results show that savings of 77.9% in the annual requirements of electricity, 65.0% in the requirements of diesel oil and 19.5% in the indoor water consumption can be achieved. Finally, the Jordanian green building model had achieved 44 points in the Leadership in Energy and Environmental Design green building rating system and will have the ‘Certified’ classification.

Description: Biogas is deemed as one of the most promising renewable fuels emerging in the past several decades. At present, biogas is mainly applied to cooking for substituting fossil fuels. However, biogas is rarely reported to be used for space heating. In this paper, we designed a biogas-fired partially premixed burner for gas-fired wall-mounted boilers, which has the heat input of 25 kW and can be used for space heating and water heater tank heating. The reference gas was assumed as 60% of methane (CH4) and 40% of CO2, and the burner port area was designed as 4744.5 mm2 according to the calculation. Then, experiments were conducted to study the performance of this burner. Jet diameters were modified in order to investigate their effects on heat input, primary air ratio and flame stability of the burner. The results indicate that the burner shows superior performance when the jet diameter is 2.0 mm. Meanwhile, the primary air ratio (${alpha}^{prime }$) satisfies the design requirement. Moreover, a gas-fired wall-mounted boiler with this burner was examined to investigate the influence of different biogas composition on exhaust emissions and thermal efficiency. The results show that the concentration of CO in the flue gas meets the national standard when CH4 varied from 40% to 60% in the biogas. However, the thermal efficiency of the biogas-fired wall-mounted boiler reduces greatly with the increase of CH4 percentage.