ALBERT

Beschreibung: Consensus of continuous-time single-integrator multiagent systems with inherent nonlinear dynamics and measurement noises is addressed in this paper. The consensus controller is developed for directed interaction topologies. Each agent’s control input is constructed based on its own state and its neighbors’ states corrupted by noises. The control input contains a time-varying consensus gain in order to attenuate the noises. Conditions for ensuring mean square convergence under noisy measurement and asymptotic convergence in the noise-free case are derived. Finally, some simulations were carried out to show the effectiveness of our control law and how it can solve the consensus problem.

Beschreibung: This paper develops a generalized inventory model for exponentially deteriorating items with current-stock-dependent demand rate and permissible delay in payments. In the model, the payment for the item must be made immediately if the order quantity is less than the predetermined quantity; otherwise, a fixed trade credit period is permitted. The maximization of the average profit per unit of time is taken as the inventory system’s objective. The necessary and sufficient conditions and some properties of the optimal solution to the model are developed. Simple solution procedures are proposed to efficiently determine the optimal ordering policies of the considered problem. Numerical example is also presented to illustrate the solution procedures obtained.

Beschreibung: Considering lateral influence from adjacent lane, an improved car-following model is developed in this paper. Then linear and nonlinear stability analyses are carried out. The modified Korteweg-de Vries (MKdV) equation is derived with the kink-antikink soliton solution. Numerical simulations are implemented and the result shows good consistency with theoretical study.

Beschreibung: The interpolation-reconstruction of local underwater terrain using the underwater digital terrain map (UDTM) is an important step for building an underwater terrain matching unit and directly affects the accuracy of underwater terrain matching navigation. The Kriging method is often used in terrain interpolation, but, with this method, the local terrain features are often lost. Therefore, the accuracy cannot meet the requirements of practical application. Analysis of the geographical features is performed on the basis of the randomness and self-similarity of underwater terrain. We extract the fractal features of local underwater terrain with the fractal Brownian motion model, compensating for the possible errors of the Kriging method with fractal theory. We then put forward an improved Kriging interpolation method based on this fractal compensation. Interpolation-reconstruction tests show that the method can simulate the real underwater terrain features well and that it has good usability.

Beschreibung: Laser machining has great potential for automated manufacturing of parts made of carbon-fiber-reinforced plastic (CFRP) due to the nearly force and tool-wear free processing. The high vaporization temperatures and the large heat conductivity of the carbon fibers, however, lead to unintentional heat conduction into the material causing damage in zones close to the process. In this paper, the matrix damage zone (MDZ) is subdivided into a matrix sublimation zone (MSZ) where the matrix material was sublimated and a zone where the temperature temporarily exceeded a value causing structural damage in the matrix. In order to investigate the extent of these zones, a one-dimensional heat flow model was applied, which was calibrated by cutting experiments using temperature sensors embedded in the CFRP samples. The investigations showed that the extents of the MSZ and MDZ are dominated by a total interaction time, which includes the passage of the laser beam and the continued interaction of the cloud of hot ablation products with the carbon fibers at the kerf wall and that from a practical point of view, the experimentally determined effective heat conductivity is suitable for simple estimations of the heat-affected zones in CFRP.

Beschreibung: This paper is concerned with the axial buckling behavior of multi-walled silicon carbide nanotubes (MWSiCNTs) based upon a molecular mechanics model. To this end, the mechanical properties of silicon carbide sheets are obtained according to the density functional theory within the framework of the generalized gradient approximation. Through establishing a linkage between the quantum mechanics and the molecular mechanics, the force constants of the total potential energy are obtained theoretically. A closed-form expression is proposed from which by knowing the chirality of the MWSiCNT, its critical buckling strain can be calculated as quickly and accurately as possible. The effects of chirality and number of walls on the critical buckling strain of MWSiCNTs are carefully investigated. It is concluded that with increasing the number of walls of nanotubes, their stability decreases. The effects of diameter and number of walls on the critical buckling strain of MWSiCNTs under axial load get more pronounced at lower diameters. Besides, it is found that the minimum critical buckling strain is related to nanotubes with \( (n,\frac{n}{2}) \) chiral vectors.

Beschreibung: The existing material classification is proposed to improve the inventory management. However, different materials have the different quality-related attributes, especially in the aircraft industry. In order to reduce the cost without sacrificing the quality, we propose a quality-oriented material classification system considering the material quality character, Quality cost, and Quality influence. Analytic Hierarchy Process helps to make feature selection and classification decision. We use the improved Kraljic Portfolio Matrix to establish the three-dimensional classification model. The aircraft materials can be divided into eight types, including general type, key type, risk type, and leveraged type. Aiming to improve the classification accuracy of various materials, the algorithm of Support Vector Machine is introduced. Finally, we compare the SVM and BP neural network in the application. The results prove that the SVM algorithm is more efficient and accurate and the quality-oriented material classification is valuable.

Beschreibung: Arrays of diamond photoemitters with silicon-vacancy (SiV) photoluminescent (PL) centers have been produced by epitaxy of CVD diamond inside laser-ablated channels in a-Si mask on single crystal or polycrystalline diamond substrates, the mask also serving as Si-doping source. Strong PL emission from the SiV centers with zero-phonon line at 738.6 nm wavelength (6 nm width, 0.8 ns decay time), localized within the photoemitters, has been measured.

Beschreibung: Graphene/nickel composite materials were successfully prepared via a one-step in situ reduction from nickel chloride, graphene oxide, and hydrazine at 80 °C for 3 h. Face-centered cubic Ni nanostructures with uniform size and high dispersion assembled on graphene sheets. Through the measurement of complex relative permittivity and permeability, their microwave absorption properties were evaluated. In comparison with pure Ni nanoparticles and graphene, the composite materials demonstrated much better characteristics of microwave absorption. The lowest reflection loss value of the composites with a thickness of 3 mm can reach −23.3 dB at 7.5 GHz. Our research reveals that graphene/Ni composites are promising microwave absorption materials with desirable absorption properties and reduced material weight.

Beschreibung: In this paper, a non-contact method that allows to determine the carrier concentration in CdSe crystals is presented. The method relies on the measurement of the effective infrared absorption coefficient by means of the photothermal infrared radiometry (PTR). In order to obtain the effective infrared absorption coefficient and thermal diffusivity, the frequency characteristics of the PTR signal were analyzed in the frame of a one-dimensional heat transport model for infrared semitransparent crystals. The carrier concentrations were estimated using a theory introduced by Ruda and a recently proposed normalization procedure for the PTR signal. The deduced carrier concentrations of the investigated CdSe crystals are in reasonable agreement with those obtained using Hall measurements and infrared spectroscopy. The method presented in this paper can also be applied to other semiconductors with the carrier concentration in the range of 10 14 –10 17  cm −3 .

Beschreibung: The presence of wool fibres in non-woven Alfa fibres sheet was investigated as a mean of improving adhesion of Alfa fibre-reinforced unsaturated polyester composite. FT-IR and Raman spectroscopy results revealed that such improvement could occur by a decrease in the hydrophilic character of the Alfa fibres owing to the presence of wool fibres. Hence, physical and chemical interactions could happen between the reinforcement and the matrix as demonstrated by FT-IR and Raman spectroscopy results. Tensile testing performed on this composite confirmed that such adhesion could occur according to its excellent specific parameters despite of its low tensile strength attributed to a higher fibre to fibre contact of wool fibres.

Beschreibung: X-ray fluorescence (XRF) is a well known nondestructive technique. It is also applied to multilayer characterization, due to its possibility of estimating both composition and thickness of the layers. Several kinds of cultural heritage samples can be considered as a complex multilayer, such as paintings or decorated objects or some types of metallic samples. Furthermore, they often have rough surfaces and this makes a precise determination of the structure and composition harder. The standard quantitative XRF approach does not take into account this aspect. In this paper, we propose a novel approach based on a combined use of X-ray measurements performed with a polychromatic beam and Monte Carlo simulations. All the information contained in an X-ray spectrum is used. This approach allows obtaining a very good estimation of the sample contents both in terms of chemical elements and material thickness, and in this sense, represents an improvement of the possibility of XRF measurements. Some examples will be examined and discussed.

Beschreibung: Ancient turquoise Persian glazed ceramics, which are well known as Khar-Mohreh, belonged to several centuries ago. In this research, reproduction of ancient glazed bodies was performed, and the products were studied by different techniques. Experimental evaluations were focused on elemental, structural, morphological, and colorimetric characteristics. SEM micrographs illustrated a thin (10 μm) uniform composite glazed layer on a porous composite thicker layer (500 μm). The layers consist of microneedle-shaped and nanospherical particles of copper oxide distributed in an amorphous silicate medium. Modeling of this architecture was used for determination of the visual aspect of the ceramic via the reflectance coefficient. Structural and colorimetric results showed that the shape and distribution of copper oxide particles do not play a crucial role on the color of these ceramics.

Beschreibung: In this paper, the discrete random packing and various ordered packings such as tetragonal and hexagonal close packed structures generated by discrete element method and honeycomb, which is manually generated were input as the initial packing structures into the multi-particle finite element model (FEM) to study their densification during compaction, where each particle is discretized as a FEM mesh. The macro-property such as relative density and micro-properties such as local morphology, stress, coordination number and densification mechanism obtained from various initial packings are characterized and analyzed. The results show that the coupling of discrete feature in particle scale with the continuous FEM in macro-scale can effectively conquer the difficulties in traditional FEM modeling, which provides a reasonable way to reproduce the compaction process and identify the densification mechanism more accurately and realistically.

Beschreibung: In this work, magnetoresistance of as-grown and annealed n- and p-type modulation-doped Ga 0.68 In 0.32 N y As 1−y /GaAs single quantum well structures with various nitrogen concentrations has been studied. At low temperatures and low magnetic fields, in n-type samples negative and in p-type samples positive, magnetoresistance has been observed. The observed negative magnetoresistance in n-type samples is an indication of enhanced backscattering of electrons due to the weak localization of the electrons as an effect of the N-induced defects. Nitrogen concentration and thermal annealing dependence of the magnetoresistance have been studied for both n- and p-type samples. The observed decrease in the negative magnetoresistance in n-type and enhanced positive magnetoresistance in p-type samples following thermal annealing have been explained by considering thermal annealing-induced improvement of mobility and the crystal quality in N-containing samples. After thermal annealing, the magnitude of negative magnetoresistance decreases and the breaking of the weak localization is achieved at lower magnetic fields in n-type samples. It is observed that as the mobility of the sample increases, critical magnetic field of negative to positive magnetoresistance transition becomes lower.

Beschreibung: A perspective is sketched for the field of focused electron beam-induced processing (FEBIP). The FEBIP lithography technique is compared to the very successful resist-based electron beam lithography (EBL) technique. The advantages of FEBIP over EBL are identified, the main advantage being its high spatial resolution. This will enable FEBIP to become an important lithography technique for the fabrication of devices with critical dimension in the range between 1 and 20 nm and serve as a complementary technique to EBL. It will be discussed what needs to be done to achieve this and what the potential applications are.

Beschreibung: We report on the dependence of a laser radiation induced ablation process of graphite on the applied pulse duration of ultrashort pulsed laser radiation smaller than 4 ps. The emerging so-called non-thermal ablation process of graphite has been confirmed to be capable to physically separate ultrathin graphitic layers from the surface of pristine graphite bulk crystal. This allows the deposition of ablated graphitic flakes on a substrate in the vicinity of the target. The observed ablation threshold determined at different pulse durations shows a modulation, which we ascribe to lattice motions along the c axis that are theoretically predicted to induce the non-thermal ablation process. In a simple approach, the ablation threshold can be described as a function of the energy penetration depth and the absorption of the applied ultrashort pulsed laser radiation. Based on the analysis of the pulse duration dependence of those two determining factors and the assumption of an invariant ablation process, we are able to reproduce the pulse duration dependence of the ablation threshold. Furthermore, the observed pulse duration dependences confirm the assumption of a fast material specific response of graphite target subsequent to optical excitation within the first 2 ps.

Beschreibung: Ion implantation was used to dope Na acceptor into ZnO single crystals. With three mixed implantation energies, uniform depth distribution of Na ion in the surface region (~300 nm) of ZnO bulk crystals is achieved. Via post-implantation annealing, a donor–acceptor pair recombination band is identified in the low-temperature photoluminescence spectra, from which the energy level of Na-related acceptor in single crystalline ZnO is estimated to be 300 meV. A p–n junction based on this ZnO–Na layer shows rectifying characteristics, confirming the p-type conductivity.

Beschreibung: The femtosecond laser color marking stainless steel surfaces with different incident wavelengths were investigated theoretically and experimentally. It indicates that the spectral regions of the colors firstly increase and then reduce with increasing spatial periods of the ripples induced by laser irradiation. Additionally, the colors are gradually changed from blue to red due to the elongation of the diffracted light wavelengths. As a result, the color effects are distinctly different. This study offers a new controllable parameter to produce diverse colors, which may find a wide range of applications in the laser color marking, art designing and so on.

Beschreibung: Tuning charge transport in the bottom-contact pentacene-based organic thin-film transistors (OTFTs) using a MoO x capping layer that serves to the electron–phonon coupling modification is reported. For OTFTs with a MoO x front gate, the enhanced field-effect carrier mobility is investigated. The time domain data confirm the electron-trapping model. To understand the origin of a mobility enhancement, an analysis of the temperature-dependent Hall-effect characteristics is presented. Similarly, the Hall-effect carrier mobility was dramatically increased by capping a MoO x layer on the pentacene front surface. However, the carrier concentration is not affected. The Hall-effect carrier mobility exhibits strong temperature dependence, indicating the dominance of tunneling (hopping) at low (high) temperatures. A mobility enhancement is considered to come from the electron–phonon coupling modification that results from the contribution of long-lifetime electron trapping.

Beschreibung: Amorphous Se 85− x Te 15 Sb x ( x  = 2.5, 5 and 7.5 at.%) thin films were deposited on glass substrates by thermal evaporation. The absorption coefficient was determined from the transmittance, and reflectance spectra in the wavelength range 400–2500 nm. Various optical constants have been calculated for the studied compositions. The mechanism of the optical absorption follows the rule of non-direct transition. It was found that the optical energy gap, E g , decreases from 1.42 to 1.36 eV with increasing Sb content from 2.5 to 7.5 at.%. These results can be interpreted on the basis of the chemical bond approach proposed by Bicermo and Ovshinsky. On the other hand, the optical constants such as refractive index, n , and extinction coefficient, K ex , of the films were studied. The dispersion of the refractive index was discussed in terms of single-oscillator Wemple–DiDomenico model. The influence of Sb content on the structure for the annealed films was investigated using X-ray diffraction (XRD) and scanning electron microscopy. The average particle size of the crystalline size for Te 0.04 Se 0.96 phase deduced from XRD pattern. This average decreases with increasing Sb content.

Beschreibung: Based on the deterministic dynamic model of electricity market proposed by Alvarado, a stochastic electricity market model, considering the random nature of demand sides, is presented in this paper on the assumption that generator cost function and consumer utility function are quadratic functions. The stochastic electricity market model is a generalization of the deterministic dynamic model. Using the theory of stochastic differential equations, stochastic process theory, and eigenvalue techniques, the determining conditions of the mean stability for this electricity market model under small Gauss type random excitation are provided and testified theoretically. That is, if the demand elasticity of suppliers is nonnegative and the demand elasticity of consumers is negative, then the stochastic electricity market model is mean stable. It implies that the stability can be judged directly by initial data without any computation. Taking deterministic electricity market data combined with small Gauss type random excitation as numerical samples to interpret random phenomena from a statistical perspective, the results indicate the conclusions above are correct, valid, and practical.

Beschreibung: This paper is concerned with the asymptotic behavior for stochastic Gilpin-Ayala competition system. The sufficient conditions for existence of stationary distribution and extinction are established. And a certain asymptotic property of the solution is also obtained. A nontrivial example is provided to illustrate our results.

Beschreibung: As the thermal conductivity of thin plates composed of tightly compressed heterogeneous layers varies continuously in the form of an exponential function, we present a nonlinear dynamical model of the fractal growth of thermal diffusion. We also analyze the quantitative relationship between the probability of growth and the disturbance term, predict the control action of the environmental disturbance term on fractal growth, and use Matlab simulation to verify the control effectiveness of thermal fractal diffusion. The results facilitate the selection of appropriate control areas and control parameters for the thermal diffusion variable coefficients. In addition, variation in the fractal dimension reflects the influence of environmental disturbance on the complex process of thermal fractal diffusion.

Beschreibung: This paper mainly discusses some dynamics asymptotic properties of autoregressive processes. By using the -dependence of random variables, we prove the least squares (LS) estimator of the unknown parameters satisfies the law of iterated logarithm.

Beschreibung: This paper proposes a space-time block coding (STBC) transmission scheme for asynchronous cooperative systems. By combination of rotated complex constellations and Hadamard transform, these constructed codes are capable of achieving full cooperative diversity with the analysis of the pairwise error probability (PEP). Due to the asynchronous characteristic of cooperative systems, orthogonal frequency division multiplexing (OFDM) technique with cyclic prefix (CP) is adopted for combating timing delays from relay nodes. The total transmit power across the entire network is fixed and appropriate power allocation can be implemented to optimize the network performance. The relay nodes do not require decoding and demodulation operation, resulting in a low complexity. Besides, there is no delay for forwarding the OFDM symbols to the destination node. At the destination node the received signals have the corresponding STBC structure on each subcarrier. In order to reduce the decoding complexity, the sphere decoder is implemented for fast data decoding. Bit error rate (BER) performance demonstrates the effectiveness of the proposed scheme.

Beschreibung: We investigate the multiple attribute decision making (MADM) problems in which attribute values take the form of interval-valued dual hesitant fuzzy information. Firstly, some operational laws for interval-valued dual hesitation fuzzy elements (IVDHFEs) based on Einstein operations are developed. Then we develop some aggregation operators based on Einstein operations: the interval-valued dual hesitant fuzzy Einstein weighted averaging (IVDHFEWA) operator, interval-valued dual hesitant fuzzy Einstein ordered weighted averaging (IVDHFEOWA) operator, interval-valued dual hesitant fuzzy Einstein hybrid averaging (IVDHFEHA) operator, interval-valued dual hesitant fuzzy Einstein weighted geometric (IVDHFEWG) operator, interval-valued dual hesitant fuzzy Einstein ordered weighted geometric (IVDHFEOWG) operator, and interval-valued dual hesitant fuzzy Einstein hybrid geometric (IVDHFEHG) operator. Furthermore, we discuss some desirable properties of these operators, and investigate the relationship between the developed operators and the existing ones. Based on the IVDHFEWA operator, an approach to MADM problems is proposed under the interval-valued dual hesitant fuzzy environment. Finally, a numerical example is given to show the application of the developed method, and a comparison analysis is conducted to demonstrate the effectiveness of the proposed approach.

Beschreibung: In the context of anomaly detection in cyber physical systems (CPS), spatiotemporal correlations are crucial for high detection rate. This work presents a new quarter sphere support vector machine (QS-SVM) formulation based on the novel concept of attribute correlations. Our event detection approach, SensGru, groups multiple sensors on a single node and thus eliminates communication between sensor nodes without compromising the advantages of spatial correlation. It makes use of temporal-attribute (TA) correlations and is thus a TA-QS-SVM formulation. We show analytically that SensGru (or interchangeably TA-QS-SVM) results in a reduced node density and gives the same event detection performance as more dense Spatiotemporal-Attribute Quarter-Sphere SVM (STA-QS-SVM) formulation which exploits both spatiotemporal and attribute correlations. Moreover, this paper develops theoretical bounds on the internode distance, the optimal number of sensors, and the sensing range with SensGru so that the performance difference with SensGru and STA-QS-SVM is negligibly small. Both schemes achieve event detection rates as high as 100% and an extremely low false positive rate.

Beschreibung: In order to realize the high accuracy attitude control of satellite with flexible appendages, attitude control system consisting of the controller and structural filter was designed. When the low order vibration frequency of flexible appendages is approximating the bandwidth of attitude control system, the vibration signal will enter the control system through measurement device to bring impact on the accuracy or even the stability. In order to reduce the impact of vibration of appendages on the attitude control system, the structural filter is designed in terms of rejecting the vibration of flexible appendages. Considering the potential problem of in-orbit frequency variation of the flexible appendages, the design method for the adaptive notch filter is proposed based on the in-orbit identification technology. Finally, the simulation results are given to demonstrate the feasibility and effectiveness of the proposed design techniques.

Beschreibung: In the present work, Ag y :TiN x thin films, obtained by reactive DC magnetron sputtering, with decreasing [N]/[Ti] atomic ratios (from 1 to 0.1) and a fixed amount of Ag pellets placed in the erosion zone of a pure Ti target, were studied envisaging their application as biopotential electrodes. The strongly under-stoichiometric samples, [N]/[Ti] = 0.1 and 10 at.% Ag; [N]/[Ti] = 0.2 and 8 at.% Ag, were found to be composed of a N-doped hcp-Ti structure, with possible formation of TiAg or Ti 2 Ag intermetallics. These samples exhibit high electrical resistivity values and low hardness and reduced modulus. In the set of samples indexed to a transition zone, [N]/[Ti] = 0.3 and 15 at.% Ag; [N]/[Ti] = 0.7 and 32 at.% Ag, a hcp-Ti to fcc-TiN phase transformation took place, giving rise to a disaggregated N-deficient TiN matrix. It correlates with the high resistivity values as well as the higher hardness and reduced modulus values that were obtained. The last identified zone comprised the stoichiometric Ag:TiN x sample—[N]/[Ti] = 1 and 20 at.% Ag. Extensive metallic Ag segregation was detected, contributing to a significant decrease of the resistivity and hardness values.

Beschreibung: The periodical removal of biodeteriogens is a fundamental need for the preservation of outdoor stone cultural heritage, which is stimulating significant efforts toward the development of low-impact conservation strategies. In the present work, the potential of laser removal of Verrucaria nigrescens Pers. from Carrara marble and the evaluation of the associated biocide effect on the organism residues embedded in the surface texture and through the outer porosities of the stone substrate were investigated. The fundamental wavelength of Nd:YAG laser (1,064 nm), commonly used in stone cleaning, and its second harmonic (532 nm) were comparatively tested. The phenomenology of laser treatments carried out in different irradiation conditions was characterized using optical, epifluorescence, and electron microscopes along with chlorophyll fluorescence with pulsed amplitude-modulated imaging. The results achieved show that 532 nm can provide significant advantages with respect to 1,064 nm. The potential of the latter against the biodeteriogens appears rather limited because of the low optical absorption, whereas the former can allow effective and practicable laser treatments, which disclose a significant application perspective.

Beschreibung: The explosion of health-related costs in U.S. firms over more than a decade is a huge concern for managers. The initiation of Health and Safety (H&S) programs at the firm level is an adequate Corporate Social Responsibility (CSR) initiative to contain this evolution. However, in spite of their documented efficiency, firms underinvest in those programs. This appears as a puzzle for health economists. In this paper, we uncover a strong negative relation of financial leverage to the implementation of H&S programs. The negative impact of debt on investment and CSR activities is generally interpreted as an efficient disciplinary effect of debt on managers. H&S are particularly well suited to revisit this evidence, given their strong profitability and homogeneity across firms. Very interestingly, the negative effect is stronger for firms with high free cash flows, for which debt is used to prevent overinvestment. This strongly suggests that debt, while disciplining managers, also discourages investments which are valuable both for firms and society.

Beschreibung: Although polynomial NARX models have been intensively used in nonlinear system identification, few papers discussed how to relate the inner nonlinearities to specific types of clusters and regressors. The objective of this paper is to discuss this relationship for a class of systems that contain even or odd nonlinearities. This class covers block-structured models (Hammerstein, Wiener, and others) and systems with dynamic nonlinearities. To achieve the paper’s aim, a deep frequency-domain analysis is performed. For each type of nonlinearity, all the NARX clusters are investigated and the results show that each regressor type provides specific nonlinear contribution. The investigation is based on an output power spectra analysis when a specific multisinusoidal excitation is applied. According to the spectral contributions in some of the frequency lines, the nonlinearity classification is possible. By applying the same procedure to the clusters, one interprets how these clusters can (or not) contribute to explain the system nonlinearity. The paper findings have two major impacts: (i) one gains deep knowledge on how the nonlinearities are coded by the clusters, and (ii) this information can be used, for instance, to aid a structure selection procedure (ERR, term clustering, etc.) during the discarding of the clusters which are not able to explain the system nonlinear behavior. Some practical and experimental aspects are discussed, while numerical examples are presented to show the validity of the theoretical analysis.

Beschreibung: The aim of this paper is to analyze load-carrying capacity of redundant free-floating space manipulators (FFSM) in trajectory tracking task. Combined with the analysis of influential factors in load-carrying process, evaluation of maximum load-carrying capacity (MLCC) is described as multiconstrained nonlinear programming problem. An efficient algorithm based on repeated line search within discontinuous feasible region is presented to determine MLCC for a given trajectory of the end-effector and corresponding joint path. Then, considering the influence of MLCC caused by different initial configurations for the starting point of given trajectory, a kind of maximum payload initial configuration planning method is proposed by using PSO algorithm. Simulations are performed for a particular trajectory tracking task of the 7-DOF space manipulator, of which MLCC is evaluated quantitatively. By in-depth research of the simulation results, significant gap between the values of MLCC when using different initial configurations is analyzed, and the discontinuity of allowable load-carrying capacity is illustrated. The proposed analytical method can be taken as theoretical foundation of feasibility analysis, trajectory optimization, and optimal control of trajectory tracking task in on-orbit load-carrying operations.

Beschreibung: The photovoltaic behaviour of metal/n-InGaN Schottky junction solar cells with low- and high-level injection conditions are explored by using voltage model. Four metals Ni–Au, Ni, Au and Pt are used as Schottky contact with n-InGaN and Schottky junction solar cell studied for open-circuit voltage ( V oc ) and short circuit current density ( J sc ) with a variation of Indium composition in n-InGaN. The cut-off value of Indium composition in n-InGaN is 36, 42, 55 and 70 % for Ni–Au, Ni, Au and Pt, respectively. The effects of doping density and surface recombination velocity on V oc and J sc are also explored. Model predict increment in V oc and J sc under high-level injection condition as compared to low-level injection condition with ϕ  = 2 × 10 17  cm −2  s −1 photon flux. The metal, Pt, is found to be a better choice in terms of making Schottky junction with n-InGaN. The concentration of donor atoms in n-InGaN plays an important role in both types of injection. The donor concentration should preferably be kept higher (〉10 16  cm −3 ) to get higher V oc .

Beschreibung: BiVO 4 nanocrystals coupled with Ag nanoparticles (Ag–BiVO 4 heterogeneous nanostructures) have been prepared by a new strategy via combining a hydrothermal route with a polyol process, in which BiVO 4 nanocrystals were first synthesized by a hydrothermal route, and then, Ag nanoparticles were grown on the surfaces of the presynthesized BiVO 4 nanocrystals through a polyol process. The photocatalytic evaluations demonstrate that BiVO 4 nanocrystals coupled with Ag nanoparticles exhibit the enhanced visible-light-driven photocatalytic activity for the degradation of methylene blue (MB) and rhodamine B (RhB). The energy alignment and diffuse reflectance property of Ag–BiVO 4 heterogeneous nanostructures demonstrate that Ag nanoparticles attached on the surfaces of BiVO 4 nanocrystals play double roles for the enhanced visible-light-driven photocatalytic activity. First, the Ag nanoparticles grown on the surfaces of BiVO 4 nanocrystals may act as electron sinks to retard the recombination of the photogenerated electrons and holes in BiVO 4 so as to improve the charge separation on its surfaces. Second, the Ag nanoparticles increase the visible light absorption of the Ag–BiVO 4 photocatalyst due to surface plasmon resonance (SPR) of Ag nanoparticles. These double roles of Ag nanoparticles make Ag–BiVO 4 heterogeneous nanostructures to exhibit the enhanced photocatalytic activity to decompose MB and RhB under visible light irradiation, compared to the pure BiVO 4 nanocrystals. The enhanced photocatalytic activity is attributed to the charge transfer from BiVO 4 to the attached Ag nanoparticles as well as SPR absorption of Ag nanoparticles. The present work not only provides an efficient route to enhance visible-light-driven photocatalytic activity of BiVO 4 , but also offers a new strategy for fabricating metal–semiconductor heterogeneous nanostructure photocatalysts, which are expected to show considerable potential applications in solar-driven wastewater treatment and water splitting.

Beschreibung: We revisit the derivation of a nonlocal problem modelling temperature distribution due to power generation using thermoelectric effect. The problem has nonlocal coefficients in reaction and convection terms rather than diffusion term, which makes the problem more interesting. In this paper, we prove that the nonlocal problem has a unique decreasing solution when electric current induced by the thermoelectric effect is small enough.

Beschreibung: This paper shows the development of an approximate analytical solution of radial consolidation by prefabricated vertical drains with a threshold gradient. To understand the effect of the threshold gradient on consolidation, a parametric analysis was performed using the present solution. The applicability of the present solution was demonstrated in two cases, wherein the comparisons with Hansbo’s results and observed data were conducted. It was found that (1) the flow with the threshold gradient would not occur instantaneously throughout the whole unit cell. Rather, it gradually occurs from the vertical drain to the outside; (2) the moving boundary would never reach the outer radius of influence if , whereas it will reach the outer radius of influence at some time; (3) the excess pore pressure will not be dissipated completely, but it will maintain a long-term stable value at the end of consolidation; (4) the larger the threshold gradient is, the greater the long-term excess pore pressure will be; and (5) the present solution could predict the consolidation behavior in soft clay better than previous methods.

Beschreibung: Peer-to-peer (P2P) file distribution imposes increasingly heavy traffic burden on the Internet service providers (ISPs). The vast volume of traffic pushes up ISPs’ costs in routing and investment and degrades their networks performance. Building ISP-friendly P2P is therefore of critical importance for ISPs and P2P services. So far most efforts in this area focused on improving the locality-awareness of P2P applications, for example, to construct overlay networks with better knowledge of the underlying network topology. There is, however, growing recognition that data scheduling algorithms also play an effective role in P2P traffic reduction. In this paper, we introduce the advanced locality-aware network coding (ALANC) for P2P file distribution. This data scheduling algorithm completely avoids the transmission of linearly dependent data blocks, which is a notable problem of previous network coding algorithms. Our simulation results show that, in comparison to other algorithms, ALANC not only significantly reduces interdomain P2P traffic, but also remarkably improves both the application-level performance (for P2P services) and the network-level performance (for ISP networks). For example, ALANC is 30% faster in distributing data blocks and it reduces the average traffic load on the underlying links by 40%. We show that ALANC holds the above gains when the tit-for-tat incentive mechanism is introduced or the overlay topology changes dynamically.

Beschreibung: This paper explores the strategies organizations use to demonstrate their accountability for biodiversity and legitimize their impact in this area through the use of techniques of neutralization. Neutralization aims to manage stakeholder impressions on very socially sensitive issues. Based on the content analysis of 148 sustainability reports from mining organizations, the study sheds light on the successful use of rhetoric in reports on non-measurable and potentially unaccountable issues. Specifically, the study shows that mining organizations use four main techniques of neutralization when they explain their impact on biodiversity. When they address stakeholders, they defend their social legitimacy and environmental responsiveness using one of the four techniques: they claim of a net positive or neutral impact on biodiversity, they deny that they have a significant impact, they distance themselves from the impact of their actions, and they play down their responsibilities. The study contributes to the literature on corporate sustainability and accounting for stakeholders. It focuses on under-researched issues such as the management of biodiversity and the tactics used to rationalize negative impacts. The study also bridges the gap between theories about organizational legitimacy, impression management, and techniques of neutralization.

Beschreibung: Historical scientists frequently face incomplete data, and lack direct experimental access to their targets. This has led some philosophers and scientists to be pessimistic about the epistemic potential of the historical sciences. And yet, historical science often produces plausible, sophisticated hypotheses. I explain this capacity to generate knowledge in the face of apparent evidential scarcity by examining recent work on Thylacoleo carnifex , the ‘marsupial lion’. Here, we see two important methodological features. First, historical scientists are methodological omnivores, that is, they construct purpose-built epistemic tools tailored to generate evidence about highly specific targets. This allows them to produce multiple streams of independent evidence and thus maximize their epistemic reach. Second, investigative scaffolding: research proceeds in a piece-meal fashion, information only gaining evidential relevance once certain hypotheses are well supported. I illustrate scaffolding in a discussion of the nature of functional ascription in paleobiology. Frequently, different senses of ‘function’ are not discriminated during paleobiological investigation—something which can mar adaptationist investigations of extant organisms. However, I argue that, due to scaffolding, conflating senses of ‘function’ can be the right thing to do. Coarse-grained functional hypotheses are required before it is clear what evidence could discriminate between more fine-grained ones. I draw on omnivory and scaffolding to argue that pessimists make a bad empirical bet. It is a bad idea to bet against the epistemic fortunes of such opportunistic and resourceful scientists, especially when we have reason to think we will systematically underestimate the amount of evidence ultimately available to them.

Beschreibung: In most of the hazardous material transportation problems, risk factors are assumed to be constant, which ignores the fact that they can vary with time throughout the day. In this paper, we deal with a novel time-dependent hazardous material transportation problem via lane reservation, in which the dynamic nature of transportation risk in the real-life traffic environment is taken into account. We first develop a multiobjective mixed integer programming (MIP) model with two conflicting objectives: minimizing the impact on the normal traffic resulting from lane reservation and minimizing the total transportation risk. We then present a cut-and-solve based -constraint method to solve this model. Computational results indicate that our method outperforms the -constraint method based on optimization software package CPLEX.

Beschreibung: We present the hierarchical interactive lasso penalized logistic regression using the coordinate descent algorithm based on the hierarchy theory and variables interactions. We define the interaction model based on the geometric algebra and hierarchical constraint conditions and then use the coordinate descent algorithm to solve for the coefficients of the hierarchical interactive lasso model. We provide the results of some experiments based on UCI datasets, Madelon datasets from NIPS2003, and daily activities of the elder. The experimental results show that the variable interactions and hierarchy contribute significantly to the classification. The hierarchical interactive lasso has the advantages of the lasso and interactive lasso.

Beschreibung: Train-induced vibration of steel truss bridges is one of the key issues in bridge engineering. This paper talks about the application of tuned mass damper (TMD) on the vibration control of a steel truss bridge subjected to dynamic train loads. The Nanjing Yangtze River Bridge (NYRB) is taken as the research object and a recorded typical train load is included in this study. With dynamic finite element (FE) method, the real-time dynamic responses of NYRB are analyzed based on a simplified train-bridge time-varying system. Thereinto, two cases including single train moving at one side and two trains moving oppositely are specifically investigated. According to the dynamic characteristics and dynamic responses of NYRB, the fourth vertical bending mode is selected as the control target and the parameter sensitivity analysis on vibration control efficiency with TMD is conducted. Using the first-order optimization method, the optimal parameters of TMD are then acquired with the control efficiency of TMD, the static displacement of Midspan, expenditure of TMDs, and manufacture difficulty of the damper considered. Results obtained in this study can provide references for the vibration control of steel truss bridges.

Beschreibung: The flow rate variation of the drilling fluid and micro-overflow loss is difficult to analyze. The purpose to prevent the occurrence of kick, lost circulation, and other complex conditions is not easy to be achieved. Therefore, the microflow-induced annulus multiphase flow rate and annulus pressure field model were studied, and a downhole microflow measurement system has been developed. A differential pressure type flow measurement was used in the system, and real-time downhole information was obtained to achieve deep, narrow windows and other safety-density complex formation security. This paper introduced a new bottom-hole flow meter which can measure the annular flux while drilling and monitor overflow and circulation loss. The accuracy and reliability of the MPD (managed pressure drilling) system can be improved obviously by applying the device; as a result, the safety of drilling is enhanced and the cost is reduced.

Beschreibung: In the present work, graphene oxide (GO) was prepared by hummers method from natural graphite and modified with iron oxide nanoparticles. The structural order and textural properties of the graphene-based materials were studied by TEM, XRD, TG-DTA and FT-IR. Hydrogen adsorption measurements have been carried out at 77 or 87 K, and atmospheric pressure on graphene oxide and Fe 3 O 4 –graphene oxide materials. Hydrogen adsorption at 77 K and atmospheric pressure reached values in the order of 1.7 and 2.1 wt% for graphene oxide and Fe 3 O 4 –graphene oxide materials, respectively. The hydrogen adsorption capacities of the Fe 3 O 4 –graphene oxide materials compare favorably well with those attained with high-value carbon materials. The isosteric heat of adsorption ( Q st ) was investigated as a function of hydrogen uptake at 77 and 87 K over the pressure range of 0 to atmospheric pressure. The isosteric heat of adsorption for magnetic GO (9.7 kJ mol −1 ) was found to be higher than for GO (6.1 kJ mol −1 ).