ALBERT

Description: Remote Sensing, Vol. 10, Pages 1171: Multi-Criteria Evaluation of Snowpack Simulations in Complex Alpine Terrain Using Satellite and In Situ Observations Remote Sensing doi: 10.3390/rs10081171 Authors: Jesús Revuelto Grégoire Lecourt Matthieu Lafaysse Isabella Zin Luc Charrois Vincent Vionnet Marie Dumont Antoine Rabatel Delphine Six Thomas Condom Samuel Morin Alessandra Viani Pascal Sirguey This work presents an extensive evaluation of the Crocus snowpack model over a rugged and highly glacierized mountain catchment (Arve valley, Western Alps, France) from 1989 to 2015. The simulations were compared and evaluated using in-situ point snow depth measurements, in-situ seasonal and annual glacier surface mass balance, snow covered area evolution based on optical satellite imagery at 250 m resolution (MODIS sensor), and the annual equilibrium-line altitude of glaciers, derived from satellite images (Landsat, SPOT, and ASTER). The snowpack simulations were obtained using the Crocus snowpack model driven by the same, originally semi-distributed, meteorological forcing (SAFRAN) reanalysis using the native semi-distributed configuration, but also a fully distributed configuration. The semi-distributed approach addresses land surface simulations for discrete topographic classes characterized by elevation range, aspect, and slope. The distributed approach operates on a 250-m grid, enabling inclusion of terrain shadowing effects, based on the same original meteorological dataset. Despite the fact that the two simulations use the same snowpack model, being potentially subjected to same potential deviation from the parametrization of certain physical processes, the results showed that both approaches accurately reproduced the snowpack distribution over the study period. Slightly (although statistically significantly) better results were obtained by using the distributed approach. The evaluation of the snow cover area with MODIS sensor has shown, on average, a reduction of the Root Mean Squared Error (RMSE) from 15.2% with the semi-distributed approach to 12.6% with the distributed one. Similarly, surface glacier mass balance RMSE decreased from 1.475 m of water equivalent (W.E.) for the semi-distributed simulation to 1.375 m W.E. for the distribution. The improvement, observed with a much higher computational time, does not justify the recommendation of this approach for all applications; however, for simulations that require a precise representation of snowpack distribution, the distributed approach is suggested.

Description: Remote Sensing, Vol. 10, Pages 1169: Multi-Year Analyses of Columnar Aerosol Optical and Microphysical Properties in Xi’an, a Megacity in Northwestern China Remote Sensing doi: 10.3390/rs10081169 Authors: Xiaoli Su Junji Cao Zhengqiang Li Kaitao Li Hua Xu Suixin Liu Xuehua Fan A thorough understanding of aerosol optical properties and their spatio-temporal variability are required to accurately evaluate aerosol effects in the climate system. In this study, a multi-year study of aerosol optical and microphysical properties was firstly performed in Xi’an based on three years of sun photometer remote sensing measurements from 2012 to 2015. The multi-year average of aerosol optical depth (AOD) at 440 nm was about 0.88 ± 0.24 (mean ± SD), while the averaged Ångström Exponent (AE) between 440 and 870 nm was 1.02 ± 0.15. The mean value of single scattering albedo (SSA) was around 0.89 ± 0.03. Aerosol optical depth and AE showed different seasonal variation patterns. Aerosol optical depth was slightly higher in winter (0.99 ± 0.36) than in other seasons (~0.85 ± 0.20), while AE showed its minimum in spring (0.85 ± 0.05) due to the impact of dust episodes. The seasonal variations of volume particle size distribution, spectral refractive index, SSA, and asymmetry factor were also analyzed to characterize aerosols over this region. Based on the aerosol products derived from sun photometer measurements, the classification of aerosol types was also conducted using two different methods in this region. Results show that the dominant aerosol types are absorbers in all seasons, especially in winter, demonstrating the strong absorptivity of aerosols in Xi’an.

Description: Remote Sensing, Vol. 10, Pages 1166: Inventory of Glaciers in the Shaksgam Valley of the Chinese Karakoram Mountains, 1970–2014 Remote Sensing doi: 10.3390/rs10081166 Authors: Haireti Alifu Yukiko Hirabayashi Brian Alan Johnson Jean-Francois Vuillaume Akihiko Kondoh Minoru Urai The Shaksgam Valley, located on the north side of the Karakoram Mountains of western China, is situated in the transition zone between the Indian monsoon system and dry arid climate zones. Previous studies have reported abnormal behaviors of the glaciers in this region compared to the global trend of glacier retreat, so the region is of special interest for glacier-climatological studies. For this purpose, long-term monitoring of glaciers in this region is necessary to obtain a better understanding of the relationships between glacier changes and local climate variations. However, accurate historical and up-to-date glacier inventory data for the region are currently unavailable. For this reason, this study conducted glacier inventories for the years 1970, 1980, 1990, 2000 and 2014 (i.e., a ~10-year interval) using multi-temporal remote sensing imagery. The remote sensing data used included Corona KH-4A/B (1965–1971), Hexagon KH-9 (1980), Landsat Thematic Mapper (TM) (1990/1993), Landsat Enhanced Thematic Mapper Plus (ETM+) (2000/2001), and Landsat Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS) (2014/2015) multispectral satellite images, as well as digital elevation models (DEMs) from the Shuttle Radar Topography Mission (SRTM), DEMs generated from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) images (2005–2014), and Advanced Land Observing Satellite (ALOS) World 3D 30 m mesh (AW3D30). In the year 2014, a total of 173 glaciers (including 121 debris-free glaciers) (>0.5 km2), covering an area of 1478 ± 34 km2 (area of debris-free glaciers: 295 ± 7 km2) were mapped. The multi-temporal glacier inventory results indicated that total glacier area change between 1970–2014 was not significant. However, individual glacier changes showed significant variability. Comparisons of the changes in glacier terminus position indicated that 55 (32 debris-covered) glaciers experienced significant advances (~40–1400 m) between 1970–2014, and 74 (32 debris-covered) glaciers experienced significant advances (~40–1400 m) during the most recent period (2000–2014). Notably, small glaciers showed higher sensitivity to climate changes, and the glaciers located in the western part of the study site were exhibiting glacier area expansion compared to other parts of the Shaksgam Valley. Finally, regression analyses indicated that topographic parameters were not the main driver of glacier changes. On the contrary, local climate variability could explain the complex behavior of glaciers in this region.

Description: Communal land in Indonesia often encounter controversy with investment companies including customary land rights of the Kajang tribal communities in Bulukumba. The customary rights issue of land dispute of Kajang tribal communities with PT. PP London Sumatera Indonesia has long occurred. Settlement of the protracted debate led to growing problems of social conflict. The purposes of this study are to determine, to review and to describe the process of settling customary rights of land disputes between Kajang tribe communities and PT. PP London Sumatera Indonesia in Bulukumba, South Sulawesi. This study employs a type of juridical empirics and historical studies of the existence of Kajang tribal and PT. PP London Sumatera to determine the effectiveness of the process of dispute resolution through litigation and non-litigation and the settlement impact which is not comprehensive. Based on the research results, there are deficiencies of the implementation of the Supreme Court decisi...

Description: Dried chilies (Capsicum annuum Variety Kulai) were reconstituted using two different soaking techniques (cold water and boiled water soakings), crushing and stone-grinding into a fine puree and pasteurized with and without citric and acetic acids. The quality attributes of chili puree were evaluated regarding pH, moisture, Hunter surface color (L, a, b and hue angle and chroma), extractable color (ASTA units) and capsaicinoid content. Results showed that different soaking techniques had a pronounced effect on the pH, moisture content, Hunter surface color, extractable color, hue angle and chroma of the puree. However, chili puree prepared by boiled-water soaking had lower capsaicin and dihydrocapsaicin concentrations compared to cold water soaking. Pasteurization did not seem to give an effect on the Hunter surface color (L, a, and b) and pungency of the puree produced. Overall, the combined treatments of boiled water soaking and pasteurization in the presence of a mixture of 1 ...

Description: This paper reveals the condition of religious awareness of High School Students in Kendari. Religious awareness is seen in the implementation of religious teachings that leads to the religious understanding of the students. Their religious awareness is measured in three aspects: 1) The relationship of the students with God (prayer and fasting) and the relationships of the students with other students (social interaction) and the relationship between students and themselves (food, drink and clothing and morals). The research data is collected through observation, interview and documentation method. This study indicates that religious awareness of high school students in Kendari is still low. This is due to the low and disproportionate hours of Islamic education in schools compared to the extent of subject matter that must be accepted by the students; 2). Inadequate Islamic educational facilities/infrastructures exist; 3). The professionalism of teachers of Islamic religious educa...

Description: This research specifically identifies and sets priority Key Performance Indicators (KPIs) of customer perspectives on the SME cocoa processing industry in South Sulawesi. This series of research activities include literature study, field survey, interviews, and questionnaires spread on expert responded. The method used is statistical methods and Analytical Hierarchy Process (AHP) to determine the priority ranking of KPIs in the financial perspective. The result of this research is the determination of 6 formulas and rank of KPIs. KPIs which become the performance indicator on 3 main priority sequences are the increase of profit (KPIF2) with the weight of 0.326 in the rank 1, the percentage of income increase (KPIF1) with the weight of 0.228 in the rank 2 position and the Return of Investments (KPIF3) at position 3 by weight 0.153. The priority scale of KPIs is the basis for assessing the performance of the financial aspects of the SME processing industry on the scale of SMEs.

Description: Remote Sensing, Vol. 10, Pages 1181: Improved Albedo Estimates Implemented in the METRIC Model for Modeling Energy Balance Fluxes and Evapotranspiration over Agricultural and Natural Areas in the Brazilian Cerrado Remote Sensing doi: 10.3390/rs10081181 Authors: Bruno Silva Oliveira Elisabete Caria Moraes Marcos Carrasco-Benavides Gabriel Bertani Guilherme Augusto Verola Mataveli In this study we assessed METRIC (Mapping Evapotranspiration at high Resolution with Internalized Calibration) model performance to estimate energy balance fluxes and evapotranspiration (ET) in two heterogeneous landscapes in the Brazilian Cerrado, including fluxes and ET in both agricultural and natural vegetation. The estimates were evaluated by comparing them to flux tower data collected over sugarcane (USR site), woody savanna (PDG site) and stricto-sensu savanna (RECOR site) areas. The selection of the study years (2005–2007 for USR/PDG sites and 2011–2015 for RECOR site) was based on the availability of meteorological data (to be used as inputs in METRIC) and of flux tower data for energy balance fluxes and ET comparisons. The broadband albedo submodel was adjusted in order to improve Net Radiation estimates. For this adjustment, we applied at-surface solar radiation simulations obtained from the SMARTS2 model under different conditions of land elevation, precipitable water content and solar angles. We also tested the equivalence between the measured crop coefficient (Kc_ec) and the reference evapotranspiration fraction (ETrF or F), seeking to extrapolate from instantaneous to daily values of actual evapotranspiration (ETa). Surface albedo was underestimated by 10% at the USR site (showing a better performance for full crop coverage), by 15% at the PDG site (following the woody savanna dynamics pattern through dry and wet seasons) and was overestimated by 21% at the RECOR site. METRIC was effective in simulating the spatial and temporal variability of energy balance fluxes and ET over agricultural and natural vegetation in the Brazilian Cerrado, with errors within those reported in the literature. Net radiation (Rn) presented consistent results (coefficient of determination (R2) > 0.94) but it was overestimated by 8% and 9% in sugarcane and woody savanna, respectively. METRIC-derived ET estimates showed an agreement with ground data at USR and PDG sites (R2 > 0.88, root mean square error (RMSE) up to 0.87 mm day−1), but at the RECOR site, ET was overestimated by 14% (R2 = 0.96, mean absolute error (MAE) = 0.62 mm.day−1 and RMSE = 0.75 mm day−1). Surface energy balance fluxes and ET were marked by seasonality, with direct dependence on available energy, rainfall distribution, soil moisture and other parameters like albedo and NDVI.

Description: Remote Sensing, Vol. 10, Pages 1182: Detection of Frozen Soil Using Sentinel-1 SAR Data Remote Sensing doi: 10.3390/rs10081182 Authors: Nicolas Baghdadi Hassan Bazzi Mohammad El Hajj Mehrez Zribi The objective of this paper is to evaluate the potential of Sentinel-1 Synthetic Aperture Radar “SAR” data (C-band) for monitoring agricultural frozen soils. First, investigations were conducted from simulated radar signal data using a SAR backscattering model combined with a dielectric mixing model. Then, Sentinel-1 images acquired at a study site near Paris, France were analyzed using temperature data to investigate the potential of the new Sentinel-1 SAR sensor for frozen soil mapping. The results show that the SAR backscattering coefficient decreases when the soil temperature drops below 0 °C. This decrease in signal is the most important for temperatures that ranges between 0 and −5 °C. A difference of at least 2 dB is observed between unfrozen soils and frozen soils. This difference increases under freezing condition when the temperature at the image acquisition date decreases. In addition, results show that the potential of the C-band radar signal for the discrimination of frozen soils slightly decreases when the soil moisture decreases (simulated data were used with soil moisture contents of 20 and 30 vol%). The difference between the backscattering coefficient of unfrozen soil and the backscattering coefficient of frozen soil decreases by approximately 1 dB when the soil moisture decreases from 30 to 20 vol%). Finally, the results show that both VV and VH allow a good detection of frozen soils but the sensitivity of VH is higher by approximately 1.5 dB. In conclusion, this study shows that the difference between a reference image acquired without freezing and an image acquired under freezing conditions is a good tool for detecting frozen soils.

Description: Algorithms, Vol. 11, Pages 112: A Novel Parallel Auto-Encoder Framework for Multi-Scale Data in Civil Structural Health Monitoring Algorithms doi: 10.3390/a11080112 Authors: Ruhua Wang Ling Li Jun Li In this paper, damage detection/identification for a seven-storey steel structure is investigated via using the vibration signals and deep learning techniques. Vibration characteristics, such as natural frequencies and mode shapes are captured and utilized as input for a deep learning network while the output vector represents the structural damage associated with locations. The deep auto-encoder with sparsity constraint is used for effective feature extraction for different types of signals and another deep auto-encoder is used to learn the relationship of different signals for final regression. The existing SAF model in a recent research study for the same problem processed all signals in one serial auto-encoder model. That kind of models have the following difficulties: (1) the natural frequencies and mode shapes are in different magnitude scales and it is not logical to normalize them in the same scale in building the models with training samples; (2) some frequencies and mode shapes may not be related to each other and it is not fair to use them for dimension reduction together. To tackle the above-mentioned problems for the multi-scale dataset in SHM, a novel parallel auto-encoder framework (Para-AF) is proposed in this paper. It processes the frequency signals and mode shapes separately for feature selection via dimension reduction and then combine these features together in relationship learning for regression. Furthermore, we introduce sparsity constraint in model reduction stage for performance improvement. Two experiments are conducted on performance evaluation and our results show the significant advantages of the proposed model in comparison with the existing approaches.

Description: Algorithms, Vol. 11, Pages 113: Improved Parameter Identification Method for Envelope Current Signals Based on Windowed Interpolation FFT and DE Algorithm Algorithms doi: 10.3390/a11080113 Authors: Xiangfeng Su Huaiqing Zhang Lin Chen Ling Qin Lili Yu Envelope current signals are increasingly emerging in power systems, and their parameter identification is particularly necessary for accurate measurement of electrical energy. In order to analyze the envelope current signal, the harmonic parameters, as well as the envelope parameters, need to be calculated. The interpolation fast Fourier transform (FFT) is a widely used approach which can estimate the signal frequency with high precision, but it cannot calculate the envelope parameters of the signal. Therefore, this paper proposes an improved method based on windowed interpolation FFT (WIFFT) and differential evolution (DE). The amplitude and phase parameters obtained through WIFFT and the envelope parameters estimated by the envelope analysis are optimized using the DE algorithm, which makes full use of the performance advantage of DE. The simulation results show that the proposed method can improve the accuracy of the harmonic parameters and the envelope parameter significantly. In addition, it has good anti-noise ability and high precision.

Description: Remote Sensing, Vol. 10, Pages 1186: Application of Multi-Sensor Satellite Data for Exploration of Zn–Pb Sulfide Mineralization in the Franklinian Basin, North Greenland Remote Sensing doi: 10.3390/rs10081186 Authors: Amin Beiranvand Pour Tae-Yoon S. Park Yongcheol Park Jong Kuk Hong Basem Zoheir Biswajeet Pradhan Iman Ayoobi Mazlan Hashim Geological mapping and mineral exploration programs in the High Arctic have been naturally hindered by its remoteness and hostile climate conditions. The Franklinian Basin in North Greenland has a unique potential for exploration of world-class zinc deposits. In this research, multi-sensor remote sensing satellite data (e.g., Landsat-8, Phased Array L-band Synthetic Aperture Radar (PALSAR) and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER)) were used for exploring zinc in the trough sequences and shelf-platform carbonate of the Franklinian Basin. A series of robust image processing algorithms was implemented for detecting spatial distribution of pixels/sub-pixels related to key alteration mineral assemblages and structural features that may represent potential undiscovered Zn–Pb deposits. Fusion of Directed Principal Component Analysis (DPCA) and Independent Component Analysis (ICA) was applied to some selected Landsat-8 mineral indices for mapping gossan, clay-rich zones and dolomitization. Major lineaments, intersections, curvilinear structures and sedimentary formations were traced by the application of Feature-oriented Principal Components Selection (FPCS) to cross-polarized backscatter PALSAR ratio images. Mixture Tuned Matched Filtering (MTMF) algorithm was applied to ASTER VNIR/SWIR bands for sub-pixel detection and classification of hematite, goethite, jarosite, alunite, gypsum, chalcedony, kaolinite, muscovite, chlorite, epidote, calcite and dolomite in the prospective targets. Using the remote sensing data and approaches, several high potential zones characterized by distinct alteration mineral assemblages and structural fabrics were identified that could represent undiscovered Zn–Pb sulfide deposits in the study area. This research establishes a straightforward/cost-effective multi-sensor satellite-based remote sensing approach for reconnaissance stages of mineral exploration in hardly accessible parts of the High Arctic environments.

Description: Remote Sensing, Vol. 10, Pages 1184: An Evaluation of Forest Health Insect and Disease Survey Data and Satellite-Based Remote Sensing Forest Change Detection Methods: Case Studies in the United States Remote Sensing doi: 10.3390/rs10081184 Authors: Ian W. Housman Robert A. Chastain Mark V. Finco The Operational Remote Sensing (ORS) program leverages Landsat and MODIS data to detect forest disturbances across the conterminous United States (CONUS). The ORS program was initiated in 2014 as a collaboration between the US Department of Agriculture Forest Service Geospatial Technology and Applications Center (GTAC) and the Forest Health Assessment and Applied Sciences Team (FHAAST). The goal of the ORS program is to supplement the Insect and Disease Survey (IDS) and MODIS Real-Time Forest Disturbance (RTFD) programs with imagery-derived forest disturbance data that can be used to augment traditional IDS data. We developed three algorithms and produced ORS forest change products using both Landsat and MODIS data. These were assessed over Southern New England and the Rio Grande National Forest. Reference data were acquired using TimeSync to conduct an independent accuracy assessment of IDS, RTFD, and ORS products. Overall accuracy for all products ranged from 71.63% to 92.55% in the Southern New England study area and 63.48% to 79.13% in the Rio Grande National Forest study area. While the accuracies attained from the assessed products are somewhat low, these results are similar to comparable studies. Although many ORS products met or exceeded the overall accuracy of IDS and RTFD products, the differences were largely statistically insignificant at the 95% confidence interval. This demonstrates the current implementation of ORS is sufficient to provide data to augment IDS data.

Description: Algorithms, Vol. 11, Pages 114: Revisiting Chameleon Sequences in the Protein Data Bank Algorithms doi: 10.3390/a11080114 Authors: Mihaly Mezei The steady growth of the Protein Data Bank (PDB) suggests the periodic repetition of searches for sequences that form different secondary structures in different protein structures; these are called chameleon sequences. This paper presents a fast (nlog(n)) algorithm for such searches and presents the results on all protein structures in the PDB. The longest such sequence found consists of 20 residues.

Description: Algorithms, Vol. 11, Pages 115: Color-Based Image Retrieval Using Proximity Space Theory Algorithms doi: 10.3390/a11080115 Authors: Jing Wang Lidong Wang Xiaodong Liu Yan Ren Ye Yuan The goal of object retrieval is to rank a set of images by their similarity compared with a query image. Nowadays, content-based image retrieval is a hot research topic, and color features play an important role in this procedure. However, it is important to establish a measure of image similarity in advance. The innovation point of this paper lies in the following. Firstly, the idea of the proximity space theory is utilized to retrieve the relevant images between the query image and images of database, and we use the color histogram of an image to obtain the Top-ranked colors, which can be regard as the object set. Secondly, the similarity is calculated based on an improved dominance granule structure similarity method. Thus, we propose a color-based image retrieval method by using proximity space theory. To detect the feasibility of this method, we conducted an experiment on COIL-20 image database and Corel-1000 database. Experimental results demonstrate the effectiveness of the proposed framework and its applications.

Description: Future Internet, Vol. 10, Pages 71: Hybrid Approach with Improved Genetic Algorithm and Simulated Annealing for Thesis Sampling Future Internet doi: 10.3390/fi10080071 Authors: Shardrom Johnson Jinwu Han Yuanchen Liu Li Chen Xinlin Wu Sampling inspection uses the sample characteristics to estimate that of the population, and it is an important method to describe the population, which has the features of low cost, strong applicability and high scientificity. This paper aims at the sampling inspection of the master’s degree thesis to ensure their quality, which is commonly estimated by random sampling. Since there are disadvantages in random sampling, a hybrid algorithm combined with an improved genetic algorithm and a simulated annealing algorithm is proposed in this paper. Furthermore, a novel mutation strategy is introduced according to the specialty of Shanghai’s thesis sampling to improve the efficiency of sampling inspection; the acceleration of convergence of the algorithm can also take advantage of this. The new algorithm features the traditional genetic algorithm, and it can obtain the global optimum in the optimization process and provide the fairest sampling plan under the constraint of multiple sampling indexes. The experimental results on the master’s thesis dataset of Shanghai show that the proposed algorithm well meets the requirements of the sampling inspection in Shanghai with a lower time-complexity.

Description: Future Internet, Vol. 10, Pages 70: Multidiscipline Integrated Platform Based on Probabilistic Analysis for Manufacturing Engineering Processes Future Internet doi: 10.3390/fi10080070 Authors: Lijun Zhang Kai Liu Jian Liu Researchers from different disciplines, such as materials science, computer science, safety science, mechanical engineering and controlling engineering, have aimed to improve the quality of manufacturing engineering processes. Considering the requirements of research and development of advanced materials, reliable manufacturing and collaborative innovation, a multidiscipline integrated platform framework based on probabilistic analysis for manufacturing engineering processes is proposed. The proposed platform consists of three logical layers: The requirement layer, the database layer and the application layer. The platform is intended to be a scalable system to gradually supplement related data, models and approaches. The main key technologies of the platform, encapsulation methods, information fusion approaches and the collaborative mechanism are also discussed. The proposed platform will also be gradually improved in the future. In order to exchange information for manufacturing engineering processes, scientists and engineers of different institutes of materials science and manufacturing engineering should strengthen their cooperation.

Description: The object of this paper is to numerically investigate the fluid-structure interaction of composite hydrofoil. The aim is to validate 3D numerical simulation model with fluid-structure interaction of composite materials comparing to experimental data, and study the fluid-structure interaction of composite hydrofoil. Numerical results are presented for a composite hydrofoil. The hydrofoil has unswept trapezoidal planform of aspect ratio 3.33. The numerical model has been validated and showed reasonable agreement with the experiment measurements. Then the forces and deformations of composite hydrofoil with different plying angles have been investigated at Re =1x10 6 and initial angle of attack α =6°. The results show that lift and drag coefficients and tip twist angle decrease and get minimum at about plying angle θ =35°. According to Classical Laminate Theory, the intrinsic bending-twisting coupling of composite structures leads to the variation of twi...

Description: The three-dimensional turbulent flow around plate cascades in staggered is an important factor to induce hydro-mechanical vibration. Taking the upstream three plates in side-by-side configuration and the downstream single plate in tandem configuration to form the overall staggered layout of the cascades as the subject of investigation. Based on the Large-Eddy-Simulations (LES), the forces experienced by the plates, velocity distributions and three-dimensional vortex structures around the plates are analysed in detail. Some experiments were also carried out to validate the accuracy of the numerical results by LDA measurement. The mean velocity distributions from LES results agree fairly well with the experimental results. Results show that the existence of the downstream plate hinders the development of the upstream wake and has a significant inhibitory effect on the forces experienced by the upstream plates; When the gap spacing is smaller, the stream-wise length of the reverse ...

Description: The vortex rope in the draft tube is considered as the source of the upper part load pressure pulsations, which is one of some unstable phenomena in a Francis turbine. In this study, the pressure pulsations and the vortex rope in the draft tube of a Francis turbine at upper part load operation are investigated by a three dimensional unsteady numerical method. Firstly, the main frequencies of the pressure fluctuations in three planes, which are z=0.2m, 0.4m and 0.6m, in the draft tube are obtained, which are 0.38 f n , 0.67 f n ,1.04 f n ,1.33 f n and 1.71 f n ( f n is the runner rotation frequency). The simulated main frequencies show a good agreement with the results from model tests, which are 0.34 f n and 1.72 f n . To simplify the problem in this study, the isopressuresurface of p=-25000Pa is considered as a vortex rope. It is found that the sha...

Description: Tubular reversible pump-turbine is a special machine used in tidal power, tidal fluctuation by affecting its working head was positive and negative periodic alternation, so the operating conditions of turbine power generation not only, also includes forward and reverse pump operation. A lot of researches have been done on the turbine operation at home and abroad, and a relatively mature bi-directional “s” airfoil blade has been designed, and good power generation performance has been obtained in both forward and backward directions by adding bilateral guide vanes. However, the study on the conditions of pump operation has proved dissatisfactory. In this paper, the steady numerical simulation of a water pump-turbine with bilateral guide vanes is carried out, and the internal flow of the pump operation is analyzed. The results show that by adjusting the front and rear of guide vane and blade angle combination relationship, forward and reverse operation of the pump efficiency can b...

Description: Double suction centrifugal pump has characteristics of large flow rate and high head. It is widely used in agricultural irrigation and water delivery and other projects. As the flow components, volute has a great influence on the hydraulic performance in double suction centrifugal pump. Based on the original circular section volute of the double suction centrifugal pump, the trapezoidal section volute and the horseshoe-shaped section volute were designed. By analyzing the influence of three different volutes on hydraulic performance and pressure fluctuation, it was obtained that the circular section volute had higher head in the low flow rate condition, and efficiency of the three were similar. In the design condition, the circular section volute had the highest efficiency, and head of the three were similar. The decline of the efficiency in the circular section volute was the smallest in large flow rate condition, and the head of the three were similar. Thus, the hydraulic perf...

Description: The determination of current direction from sedimentary deposits were based on silisiclastic deposits that behave differently than biogenic fragment-rich deposit. The objectives of this research are to determine biogenic sediment transport pathway of Bangka Island water, North Minahasa, by the taphonomy of benthic foraminifer Homotrema rubrum and to verify the reconstructed pathway with sea surface currents data. This study used twelve surface sediment samples that were acquired by grab sampler in 2016 and 2014-2016 annual average sea surface current data from INDESO that was generated by OPA/NEMO model. The result of this study shows that samples with higher degree of taphonomy are located closer to coral reef which forms the source of H. rubrum while samples with lower degree of taphonomy are located further from the source. Sediment transport pathway reconstructed from H. rubrum taphonomy shows inflow of water from the north and west part of the islands a...

Description: The Jakarta Bay plays an important role in supporting maritime activities such as marine transportation, tourism, industry, and coastal communities. To meet the needs of the people in the future, it is planned to build islands (giant sea wall) through huge coastal reclamation. In oceanography-point-of-view, new islands formation is believed to modify natural coastal circulation in the region. Here, we investigated the impact of new islands formation on Monsoonal circulation and passive tracer distribution by performing a validated numerical model experiment with ROMS-AGRIF. The results show that natural Monsoonal circulation is characterized by eastward (westward) flow during the Northwest (Southeast) monsoon period, but mean circulation flows eastward. Water mass in the inner bay is flushed partially by water from western/eastern peninsula. With the presence of reclaimed islands, the Monsoonal surface flows are partitioned into channels in-between the islands. An intensificatio...

Description: Cavitation phenomenon affects the reduction in performance of the pump, as it exerts significant damage to the impeller of the pump. The user should be avoid driving this phenomenon and the criterion is set as NPSHa. Along with the cavitation phenomenon, noise and vibration can occur, which can predict cavitation. This study analyzed the characteristics of vibration emitted when cavitation occurred using the accelerometers.

Description: There is usually a fluid dynamic phenomenon which involves a strong swirling flow between runner and draft tube of Francis turbines at part load condition. It is characterized by highly unsteady, large scale vortices, intense turbulence production, etc. The adverse pressure gradient in the draft tube cone can lead to vortex breakdown, which is recognized now as the main cause of hydro plant’s instabilities. Therefore, it is very significant to predict the swirling flow field exactly in design period. However, the popular Reynolds-Averaged Navier-Stokes (RANS) or large eddy simulation (LES) method also has some shortcomings in CFD analysis, such as inaccurate large structures resolution or restrictive grid requirement. Very large eddy simulation(VLES), as a hybrid RANS/LES methodology, could combine the advantages of different turbulence approaches of RANS, LES, which has been proved by many authors. This paper presents a VLES case-study, based on the experimental studies of the ...

Description: The flow types between the guide vanes have significant influence on the stability of a pump-turbine, especially when the guide vane opening is very small. In order to study the flow types between the adjacent vanes, the CFD simulation, which with the Reynolds Stress Model, of a cascade with three kinds of water foil were carried out, and a verification experiment about the cascade flow was conducted. The CFD simulation results indicated that the diffusion ratio and leading edge curvature ratio of the water foil are the important parameters which make the different flow types happened. Moreover, the experiment results show that the CFD simulation has a great agreement with it.

Description: The Gobo/Hidaka coastal area is known for its pristine nature and biodiversity, but recent urban developments might have affected its environmental condition. In previous study, we found a relatively low amount of organic matter from the Hidaka Port samples. In this study, we determine the possible cause of such an anomalous low organic matter content. Sludge samples were collected from the bottom of the sea of Hidaka Port monthly for one year (July 2016 to June 2017). The result showed the lowest content of organic matter in July 2016 (0.89%) and almost repeated in November 2016 (1.47%), February 2017 (1.08%), and May 2017 (1.42%). Meanwhile, the highest record was in June 2017 (3.93%). The fluctuating organic contents are in congruent with the water temperature data. The possible interactions among the seawater temperature, monthly rainfall amount of the corresponding months, possible abundance of marine microbes, and farming in the surrounding area might have caused the fluct...

Description: Backflow usually exists at the inlet of rotors of many turbomachines at low flow rates. In counter-rotating rotors applied for the axial flow pump, such vortical structures are also able to form. In our previous researches, some broad-banded pressure fluctuations in low frequency range have been observed between front and rear rotors, but we have not yet been able to explain what causes such phenomenon. In this study, in order to find out the causes of low frequency components at low flow rates, unsteady numerical simulations for the whole front and rear rotors are conducted, and casing pressure is experimentally measured at the inlet and outlet of front rotor and the inlet of rear rotor. It is found that vortical structures exist between front and rear rotors at below 40% of design flow rate. These vortices seem to be the result of shear layer instability at the impingement location of the exiting flow from front rotor to the backflow of rear rotor. The behaviours of these back...

Description: Mixing performance of the solid-liquid two phase system in a mixing tank equipped with a logarithmic spiral impeller is studied with fluid dynamics software FLUENT. Based on the kinetic theory of granular flow, the basic control equations of the E-E model are established. A multiple reference frame (MRF) method and the RNG k - ε turbulence model are chosen to simulate solid-liquid flow performance and results are compared with that of the four blade turbine (MK) and the six blade turbine (PY). Research shows that the logarithmic helicoidal impeller improves solid-liquid axial-flow performance, and the concentration, power consumption and the mixing time of it are better compared with the PY and MK impellers. For a wide range of mixing velocities, the concentration of the sludge particles is always lower in the upper position to impeller than in the lower position. With the increase of velocity, the power consumption raises gradually, the uniformity of solid particle ...

Description: Foraminifera is potential bioindicator to understand the modern and ancient marine environment and have been widely used as bioindicator. Java Sea to Flores Sea are productive area influenced by physical and chemical reactions from nature and human activity, so that their characteristics are important to recognize. The aim of this research is to determine oceanography condition of Java Sea to Flores Sea covers the depth, temperature, thermocline, and upwelling according to foraminifera analysis. The method used were inventory and species analysis from 12 stations along study area. The analysis was conducted based on species and abundance. Foraminifera species which are warm water bioindicators are Globigerinoides rubra and Globigerinoides sacculifera, upwelling bioindicators are Globigerina bulloides and Globorotalia menardii, and shallow thermocline bioindicators are Pulleniatina obliqueloculata and Neogloboquadrina dutertrei. The resul...

Description: The most commonly used method to control the pre-tightening load of the bolt is torque measurement method and strain gauge method. The torque measurement method is convenient to use but usually leads to large control error, even up to ±25%. The strain gauge method is able to provide adequate control accuracy but is not convenient to use and costs are high. This study attempts to combine the advantages of the torque measurement method and the strain gauge method to form a kind of bolt pre-tightening force control method which is convenient for engineering application.

Description: The blade tip clearance is inevitable for an axial flow rotor. The clearance flow contains various vortices and the resulting vortex cavitation is a concern in hydraulic machineries. In the narrow gap, the vortex features are sensitive to the change of the clearance size, and then the geometry factors may influence the vortex cavitation characteristics. As a simplification of a blade, an isolated hydrofoil is convenient for adjusting the clearance geometries in different cases. The effects of the clearance shape, gap height and gap width on the cavitating vortices are discussed in present paper. As the limited space and the cavitation phenomenon make it difficult to measure the vortex flow features, the numerical simulation is widely used to investigate the cavitating vortices. An improved cavitation model, which is suitable for the vortex cavitation, is used in present work. Under the different geometrical conditions, the vortex structures, the pressure features and the cavitat...

Description: Currently, untapped water resources in China are mostly located in the southwestern region notable for high ranges of Qingha-Tibet Plateau, Hengduan Mountains and Yunnan-Kweichow Plateau. These water resources have the remarkable property of being high in water head within a short distance. The Pelton turbine counts as the most adequate type of water turbine to harness these water resources. An internal-controlled Pelton nozzle design is elucidated in this paper in line with the formula and an existing model in the case of a1100m water head [1]. The impact exerted by nozzle and spear angle on the nozzle hydraulic efficiency under a set of needle strokes was ascertained from the numerical perspective. Elucidated hydraulic performance of different nozzle design was anatomized. An energy criterion was proposed through acquiring the jet efficiency to select the appropriate hydraulic design of Pelton nozzle [2]. The numerical results were indicative of the design with 100°/70° combin...

Description: Acoustic target strength (TS) measurements were performed on one small pelagic fishes, and two demersal fishes, which are very important for Indonesia fisheries, namely: mackerel scad ( Decapterus macarellus ), coral trout ( Plectropomus leopardus ), and largehead hairtail ( Trichiurus sp.) on various fish sizes (fork length, FL) and orientation. The fish was successfully measured using tethered technique, where each individual fish was places and hang in web using monofilament string. The TS data analysis is performed numerically using the best-fit technique to establish the relationship between length, fish orientation, and TS. The TS-length relationship was obtained as follow: for mackerel scad, TS = TS = 20log - 84,38; for coral trout, TS = 20Log - 76,68, and for large headhairtail, TS = 20Log -91.88.

Description: Due to the difference of performance between high altitude power station and low altitude power station, environmental factors should not be neglected in the design process of turbine in high altitude area. In order to study the influence of environmental factors on the performance of hydraulic turbine. In this paper, Francis turbine in high altitude area is taken as the object of study, numerical study in considering the variation of pressure and temperature under the condition of different working condition on the performance of the turbine, and the turbine performance without considering the environmental factors were compared, when the altitude changes, the energy characteristics, cavitation performance and the flow pattern of the unit in accordance with different environmental factors are analyzed in order to reveal the influence of altitude factors on the overall performance of the turbine. The results show that when the water temperature drops, the efficiency of the unit ...

Description: Tubular turbine running environment will be affected by ocean tidal wave, under the influence of the tidal wave, the hydrodynamic performance of the tubular turbine and its water-energy conversion efficiency have become the focus of our research and discussion. This paper explores the mechanism of wave-current coupling under surface fluctuations, considering the influence of tidal wave flow and gravity influence in flow field and flow characteristics of tubular turbine. The study on the performance of the influence of hydraulic characteristics of tubular turbine under the condition of wave flow has been carried out. Results show that the wave flow conditions with considering gravity leads to mechanical runner blade be damaged by tidal wave of pressure fluctuation and cyclic extrusion, causing more serious than fatigue stress damage than no wave flow condition does which make this kind of fluid machinery practical fatigue life is reduced greatly. The condition of the wave flow co...

Description: In present work, heat transfer in heat treatment furnaces in steel industry was studied experimentally and numerically. Ansys - Fluent has been used for numerical simulation. Ansys - Fluent solvers are based on the finite volume method. Furnace geometry of numerical simulations was based on the size and dimensions of heat treatment furnace located in Esfarayen Steel Plant where experimental data have been measured. First, the evaluation of three two- equation turbulence models accompanying with experimental results were examined. The results of this study showed that the Realizable k-ε model, could predict load center line temperature better than the other two models in different times, and it is more agreed in comparison to experimental data. Second, due to study the radiation effect in numerical simulation, it was revealed that results, in a maximum error mode, showed the temperature difference 3 °C in a state without radiation to the experimental data, but this difference max...

Description: Hydropower is the largest source of renewable energy. Francis hydro turbines are the world’s most widely used hydro turbine. In this paper, CFD software used to simulate for the performance analysis of micro-class Francis hydro turbine. A draft tube is one of the most important parts of Francis turbine which connects the runner exit to the tailrace where the water is being finally discharged at atmospheric pressure from the reaction turbine. There are several issues in the draft tube like a pressure pulsation, effect of cavitation of draft tube performance, vortex rope study etc. At part-load condition vortex form, it hits structure constantly which affect the performance of the turbine. This study focused on prediction of vortex behavior at the draft tube and numerical results obtained the hydraulic performance of 3KW micro Francis turbine with the inlet pipe, a spiral casing with 12 guide vanes, 6 stay vanes and the runner 13 blades and a draft tube. Additionally, results from...

Description: Based on the ANSYS CFX software and Workbench platform, steady-state thermal analysis and static analysis of hot water circulating pump body structure are carried out when medium in the pump is 150°C. The effect of the different volute inlet width on the strength of pump body is compared. Temperature distribution, equivalent stress and total deformation of the pump body are emphatically studied when the volute inlet width is 18mm, 20mm and 22mm. The numerical simulation result shows that the change of volute inlet width affects the flow field of the hot water in the pump. With the increasing of the volute inlet width, the minimum temperature of the pump body increases firstly and then decreases. However, the maximum deformation and the equivalent stress of the pump body decreases with the increasing of the width of the volute inlet.

Description: During the runaway process of high-head turbine-generator units due to wicket gate failure, the ball valve should be closed promptly to prevent accidents, and the dynamic hydraulic characteristics during the closing process should be studied. In this paper, the flows through a prototype ball valve are simulated by the latest 3D CFD method. First, the steady flows in different openings are calculated, and we find that the headloss coefficients agree well with experimental results. Then, the water hammer led by linear closing of the ball valve is simulated by both 3D CFD and 1D Method of Characteristic (MOC), and the reasonable agreements further validate feasibility of the 3D CFD method. After that, we investigate the evolution laws of flow patterns, pressure and forces around the valve, and find that the pressure variations before, within and behind the valve differ greatly. Besides, the unstable flow fields within the valve are essential causes of pressure and force fluctuation...

Description: The plunger valve of colliding energy dissipation is one of the important parts in pipeline system. In the operation condition of low backpressure and high pressure difference, cavitation phenomenon is easy to come into being, which may result in noise and vibration and even lead to damage to valve. This article aims to decrease and even eliminate the cavitation phenomenon in plunger valve which may occur in this operation condition. Mathematical models including basic control equation, standard k-ε model, equation model of fluid, cavitation model and so on, are used to calculate flow field. Then, the physical model of plunger valve of colliding energy dissipation is built and numerical simulation study on valve’s inside flow is conducted in using software on the view of hydraulics. The physical model of plunger valve is built by using Pro/E, ICEM CFD and finally simulation is carried out by using Pumplinx software. Two calculations are performed in this study. One is calculatio...

Description: Cavitation is harmful to hydraulic machinery and equipment, which often reduces the service life and efficiency of equipment. In this paper, cavitation is further studied by studying the cavitation of the rotating disc. In this paper, the generation of the cavitation bubble in the rotating disc is numerically simulated, and the location of the low pressure zone and the relationship between the number and the speed, when the rate is less than 2000r/min, fitting the speed and minimum pressure, the fitting relation is a linear curve; the shape of the bubble coming out of the cavitation source and the position of the bubble on the rotating disk. Verified by the field test, cavitation source side of the metal and the specimen produced erosion by long time cavitation.

Description: In this paper, the mechanism of the wear of floating sleeve was analyzed firstly and according to three different pressure assumptions. The force and moment of the inner part of the floating sleeve were deduced respectively and are compared with the analog value. As a result, the force and moment of the inner part of the floating sleeve based on assumption which has minimal error can be a reference value. Then the expression of outboard force and moment were deduced. Based on the Gamultiobi() Function, the resultant and resultant moment of the eccentric 8-shaped floating sleeve were taken as objective functions. And the outer diameter, inner diameter, angle and elastic strength of the seal ring on the eccentric 8-shaped floating sleeve were taken as independent variables. With the restrained conditions of the width of seal ring, the values of the independent variables were obtained when the values of objective functions were minimum. At last, numerical simulation were carried ou...

Description: Frigate tuna ( Auxis thazard ) is widely marketed and consumed in Makassar. Most of the fresh fish for household needs are purchased from traditional mobile fish retailer (Pa’gandeng) in Makassar. However, data on the quality of fresh frigate tuna reaching the consumer of household level is still lacking. This research was conducted in three areas, namely east, south, and north of Makassar City, South Sulawesi. This study was aimed to describe the quality characteristics of fresh frigate tuna retailed by Pa’gandeng. The study was conducted by randomly taking four samples of fish from Pa’gandeng at three points of sale (sale time) in each part of the city. Physical and organoleptic parameters were measured directly at the sampling locations, while the chemical and microbiological parameters were analyzed in the laboratory. Effect of time on the fish freshness parameters were tested using ANOVA with a confidential level of 95% (α = 0.05). When ANOVA indicated the presence of ...

Description: Sustainable development can be defined in several different ways, but usually, the term refers to the definition given by the Brundtland Commission in the publication of Our Common Future. Sustainable development is often understood by relying on three pillars, namely environmental/ecology, economic and social. The demersal fishery in the South China Sea (Indonesia Fisheries Management Area / IFMA 711) became one of the supporting sectors of the economy of the fishermen communities around of these waters. This study aims to analyze the sustainability of demersal fisheries with the Sustainability Window (SuWi) approach. Demersal fishery sustainability condition in the South China Sea (IFMA 711) waters tend to be better from year to year. However, the width of demersal sustainability window tends to be low and indicate the status of sustainability of demersal fish is not maximal in the South China Sea (IFMA 711). Therefore, care should be taken to manage demersal fishery in the So...

Description: The Java Sea (JS) is one of the sea with unique characteristic with especially in biodiversity and oceanographic condition. The purpose of this research is to identify the EL into level 2 in Java Sea based on oceanographic condition. The Java Sea, which covers an area of 467,000 Km 2 with an average depth of 50m, is located on the Southeastern part of the Sunda Shelf. This research uses the temperature and salinity data provided by the INDESO, the sea surface height (SSH) data downloaded from the HYCOM website, and the level 2 Java Sea ecoregion shape file data from the Indonesian seas delineation team. The physical oceanographic conditions of the level 2 Java Sea ecoregions are influenced by the moonsun and their respective geographical positions. The results showed that the distribution of temperature, sea current, salinity, and Sea Surface Height differed in each Java Sea Ecoregion level 2 because it is influenced by the geographical and astronomical location of eac...

Description: When operating at part load conditions, flow separations may occur in the impeller of an axial flow pump due to the increase of the incidence angle at the impeller leading edge, probably resulting in instability in head curve. In this paper, the hump characteristic in head curve of an axial flow pump has been examined by CFD method with the help of ANSYS CFX 16.0. The results show that the head of the axial flow pump in the hump area decreased by 40% at 61% of the design flow rate, caused by stalls in the pump impeller. Furthermore, the improvement of head curve has been conducted by applying axial grooves at the wall of the pump inlet section. It is found that under the condition of small flow rates, the axial groove can effectively reduce the inlet circulation and the attack angle at the leading edge of the impeller. As a result, the back flow on the suction side of the impeller has been reduced. Consequently, the hump phenomenon in the head curve of the axial flow pump has be...

Description: The opening degrees of guide vane and runner blade are adjustable for Kaplan units. Therefore, the prototype unit performance is evaluated by cam curves to ensure the maximum efficiency points at different runner blade or guide vane angles. In this paper, the numerical simulation method is used to obtain the cohesive curves. The gravity force term is not ignored in the calculation, of which the effects are analysed not only on prototype performances, but also on internal flow characteristics such as the streamlines around runner blades, the pressure distributions and the head losses of each part.

Description: The hydraulic performance of Pelton turbine is different from reaction turbines due to its unsteady flow of rotating buckets with time and space. The water sheet flow in Pelton turbine is also very complex as the jet flow is often interacted with air and itself. This paper numerically investigates the dynamic hydraulic performance of a Pelton under super-high head. Unsteady numerical simulations were performed using SST k - ω . Two-phase homogeneous model and VOF were adopted to model he free surface flow. The evolution history of water sheet flow in the buckets were presented. The distribution of pressure coefficient on the bucket surface were also analysed. The results indicate that the development of water sheet flow on the bucket surface can be divided into three stages, corresponding to the output power variation process. This calculation can be used to illustrate the hydraulic mechanism of water sheet flow evolution.

Description: The vibration and noise of large Francis-turbine units tends to increase, the efficiency decreases and the units operate unstably if the units operate under the cavitation condition. Hence it must be eradicated completely that the units run under the cavitation condition. Nowadays, the judgment of inception cavitation of model Francis-turbine runner blades remains stagnant at the stage of artificial observation so that the results lacks of objectivity and consistency. An auto-test method based on acoustics theory and the principle of cavitation is presented. When cavitation happens, the acoustic energy radiated by bubbles while collapsing is different at different stages of cavitation, for the size and number of bubbles are different. And therefore the distribution of cavitation noise energy in the frequency domain varies along with the severe degree of cavitation, according to which the inception cavitation can be determined exactly by acquiring the acoustics signals in the wat...

Description: A new concept of power generator using autorotation of elliptic cylinder to extract energy from fluid is proposed in the present study. Numerical simulation studies Fluid-Structure Interaction of the fixed-axis autorotation of rigid elliptic cylinder using a coupled Computational Fluid Dynamics (CFD) – Rigid Body Dynamics (RBD) solver. This solver requires no solid mesh to setup FSI (Fluid Structure Interaction) simulation. Based on solving two-dimensional unsteady incompressible N-S equations and SST k - ω turbulent governing equations, the power generator of elliptic cylinder was investigated in different axis rations, eccentric distance ratios and Reynolds number conditions. Numerical results reveal that autorotation of elliptic cylinder can achieve energy extraction. With optimal parameters, the power generator can reach maximum energy extraction efficiency of 34%. The investigation results provided fundamental support for utilization of ocean current energy.

Description: Mechanical losses of large titling-pad journal bearings are increasing with higher rotational speed. However, mechanical losses of loaded and unloaded pads vary largely. This study analyzes the reason of varying mechanical losses in different pads. A three dimensional model is built for a full large tilting-pad journal bearing. The real backflow environment of journal bearings can be an important factor influencing lubricant viscosity and bearing mechanical loss. Thus, two boundaries, full-oil backflow and full-air backflow in two sides of the bearing, are simulated and compared with the experimental data of S.Taniguchi. Apart from the backflow lubricant, the gaseous cavitation and SST turbulence model are included in bearing simulations. Compared with experimental data, SST model is proved to be more suitable than laminar model for simulations. While the mechanical loss simulated by SST model with oil backflow is much higher than experimental data, the mechanical loss of the jo...

Description: The development of hydropower in China has entered the gold period nowadays. Numerous challenging hydropower projects have been presented to researchers and scholars. In order to adapt to this trend and the need of the nation, TOPsys, an one dimensional simulation software based on the method of characteristics (MOC) for hydraulic transients, has been developed in State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University recently. This software has been employed for transient flow simulations of more than thirty hydropower stations in China and overseas. The whole paper is organized as follows: first, basic mathematical theory of the software was introduced. Subsequently, several typical engineering applications, including conventional power stations and pumped storage power stations, were given for validation. Finally, the versatility as well as the expandability of this software was shown with several special engineering examples.

Description: This paper introduces a water turbine which is used to recycle rich energy for hydraulic cooling towers. That cooling tower’s head are from a few meters to more than ten meters, and mass flow is from 300t/h to 1300t/h. The water turbine has a small radius size, a long and narrow flow passage and higher velocity, so the hydraulic loss in spiral casing and stay vane is too high to decrease the hydraulic efficiency. To decrease hydraulic loss, three diversion components with different spiral casing and stay vanes are introduced. When the radial dimension of the spiral casing is same, the double-spiral casing with the same rectangle section, a spiral casing with same rectangle section and stay vane, and a common spiral casing according to the same circumferential velocity rules are designed. The simulation results show that the hydraulic efficiency of the water turbine for same rectangle section spiral casing and stay vane is highest, and that for constant circumferential velocity s...

Description: Sediments have been used as an indicator of environmental pollution because of its role as a final sink for most of materials. This study aims to describe the chemical characteristics of 13 metal contents in surface sediments and to predict the source of metal using enrichment factor (EF) approach. During the Java-Makassar-Flores (JMF) Triangle experiment in August 2015, about 11 surface sediment samples were collected using Multicore Octopus. Here we analyzed only three sediment samples at sampling station close to the coast of Java (MC-09), at mid-Java Sea (MC-11) and close to the coast of Kalimantan (MC-13). The result show that surface sediments consist of olive loose sand to silty clay containing organic materials, foraminifera shells, fragments of litic and quartz with dominant color of olive. The result of total metal analysis yields Al as the most dominant element in all stations. The enrichment factor (EF) revealed that the surface sediments of Java Sea enriched ...

Description: With the development of offshore oilfield, the gas-liquid centrifugal multiphase pump (CMP) has become the focus of research for its more effective way of working and economic benefits. In order to transport two-phase media, the internal flow of gas-liquid multiphase pump is complicated. In this study, the gas content effect on CMP performance was investigated by computational fluid dynamics (CFD). Gas and water are flowed through a DN127 CMP at varying gas content. This paper based on the Euler Model, the numerical simulation and analysis of three stages gas-liquid two-phase pump internal flow field are conducted, with the standard k - ε , SST and SSG turbulence model. The influence of different turbulence models on the numerical results and the effects of different gas-liquid fraction on the characteristics of pump and internal flow law are analyzed. The results shows that the standard SST turbulence model is more suitable for the numerical calculation of gas-liquid...

Description: Volatile components are groups of compounds which could affect the aroma and acceptance of commodities. The objective of this research was to identify volatile components of two most common freshwater commodities in Indonesia which are patin catfish ( Pangasius hypophthalmus ) and nile tilapia ( Oreochromis niloticus). The method used in this study were to detect volatile compounds using Gas Chromatography/Mass Spectrometry (GC/MS) on both fresh fish samples with Solid Phase Micro Extraction (SPME) as an initial extraction method. The volatile components analysis successfully detects and identify as many as 46 volatiles compounds in raw nile tilapia and 59 compounds were detected in raw patin catfish. Most of the detected components came from hydrocarbons, aldehydes, alcohols and ketone groups. Most of those volatile compounds detected were derived from the results of enzymatic reactions, lipid auto oxidation and various environmental influences.

Description: Sea surface temperature (SST) is one of several indicators of climate system of the Earth. We used model SST to observe SST dataset from buoy arrays in the eastern equatorial Indian Ocean. Relationship between SST and other climate parameters can be represented in linearity approach. This approach shows that temporal variability of the SST as a dominant effect. Linear model fitting (LMF) has been examined with four treatments, with and without: covariate transformation, interaction, centering, and addition time covariate in the model. The LMF chosen as basic construction in the model with covariate interaction combination and transformation, which increases magnitude of multiple-R 2 (56.62%) and adjusted-R 2 (56.13%), i.e. 0.31% and 0.43% respectively. This shows that time covariates have a strong significance effect in the model, compared to continuous covariates. However, the model has autocorrelation, which has large Akaike Information Criterion (AIC) valu...

Description: On-orbit refuelling of spacecraft is one of the main on-orbit service modes, which is the main technical means to increase the working life and improve the economic efficiency of the spacecraft. The vane type tank is one of the most advanced tanks, which can manage all of the propellant. The vane device is the form of propellant management for the low-gravity expulsion of propellant form spacecraft. The orbital propellant management is achieved by the vane type propellant tank. The fluid reorientation and refilling in space environment is the key technology of on-orbit refuelling. However, the experiment verification of the vane type in microgravity environment couldn’t be given for a long time. Therefore, numerical simulation is necessary for the study of on-orbit refueling. Focusing on the research of the vane type tank of on-orbit refueling, by using a VOF two-phase flow model, the fluid behavior in microgravity environment and the flow characteristic of the refueling process...

Description: Pumped-storage can quickly and flexibly respond to adjust the grid fluctuation and keep the grid stability because of its various functions. Besides, it is an effective power storing tool and now it has become the largest and most widely used energy storage form. Many countries configured a certain proportion of pumped storage power in the network to keep their grid stability. This paper introduces the current development status of the pumped storage power (PSP) station in some different countries based on their own economic demands and network characteristics. Then the evolutions of the pumped-storage power station in China are focus reviewed. To provide better technical support for future PSP development, the typical features of the PSP in plant design, construction, operations, and economic evaluation are described in detail compared with the conventional hydropower plant. The difficulties and challenges of the pumped storage technology faced in China are also summarized and ...

Description: As the Francis turbine operated at the off-design conditions, the hydraulic instability may occurs due to the vortex rope developed in the draft tube. The swirling flow produced at the blade trailing edge has been proved to have a direct effect on the vortex rope characteristics. Research on the swirling flow is meaningful for understanding the hydraulic instability mechanisms. In this paper, the different swirling flow characteristics at part load and overload conditions were studied by numerical method. The relations between the vortex rope dynamic characteristics and the swirling flows were deeply investigated. The results showed the swirl number, which was chosen to stand for the strength of the swirling flow, changed with the vortex rope evolution. The swirl number fluctuations and its frequency were closely related to the vortex rope precession and its diameter and length. The dominant frequencies of the swirling flow in spiral vortex rope flow field were consistent with t...

Description: The impacts of climate change on hydropower development are complex, often interactive, issues. Many studies have already focused on climate change impacts on the hydrologic cycle. This paper downsizes the analysis and focuses on water resources for power generation. The concentration is on a review of the impacts of climate change on hydropower development from three different spatial scopes; i.e., global, national and regional scales. Climate change is a global phenomenon; however, the effects of climate change on hydropower generation are not uniform over different spatial scales. The diverse effects depend on such factors as local hydrological conditions and geographic features. This demonstrates the necessity of drilling down the analysis of climate change impacts to the sub-national, or local scale of hydropower generation. This paper characterizes both direct and indirect factors of climate change impacts on hydropower, and, elaborates on how several supporting elements c...

Description: In order to simulate the internal flow of centrifugal dredge pump accurately and efficiently, a meshfree simulation method is proposed, which is a method of smooth particle hydrodynamics (SPH). The fluid domain is discretized into Lagrangian particles, the blades, the pump body are discretized as solid particles, the governing equations for fluid, and solid mechanics are transformed into corresponding particle force. When the initial state is started, the particles move and continue to evolve under the action of these forces. The motion parameters of the flow field and solid can be obtained by interpolating the kernel function with the information of particle. The correctness of the control equations and the boundary conditions is verified by simulating the standard examples. The preliminary analysis of using this method to simulate the movement of the two-dimensional centrifugal dredge pump shows that the simulation results are reasonable. It lays theoretical basis for 3-dimens...

Description: During the operation of the pump, cavitation can cause performance drop and erosion damage to its flow parts, even can produce noise and vibration. Further, it is well known that temperature variation is of great significance for cavitation in a pump. The present paper treated the numerical analysis of cavitation in a lubricating oil pump under different temperature. In this paper, we used UGS NX to make three-dimensional model of the pump impeller and ICEM to cut the non-structural mesh of the whole flow passage. For cavitating turbulent flow simulation, a newly developed cavitation model based on Rayleigh-Plesset equation was applied. The cavitating turbulent flows in the pump impeller at different oil temperatures from 35°C to 100°C were simulated. The numerical results at different flow discharge were compared with the available experimental data. It was noted that the numerical results by the proposed cavitation model agreed fairly well with the experimental data. The resul...

Description: The clearance locate on blade root is almost 10~20 times than tip in adjustable axial flow pump, the flow in blade root clearance has obvious impact on the hydraulic characteristic in pump systems. In order to research the effect of blade root clearance on hydraulic characteristic in axial flow pump system, a vertical axial flow pump system is researched by numerical simulation and experiment. After considering the root clearance, the result has high precision under large and design flow condition. The simulation result shows with the effect of the blade root clearance, the velocity distribution from hub to shroud is trend bad, and the streamline near the blade root is changed greatly, under the same flow condition, the flow far away from the hub in the cascade is increasing, the work ability of blade is reducing, the head has a sharp fall. In this paper, only 0.5mm clearance exist, 2.9% blade surface area is loss, the head decrease 7.86%, shaft power decrease 6.35%, the efficie...

Description: The numerical investigation has been carried out on the initial stage of bubble free rise in still water. The simulation and analysis focus on the separation behavior of air bubbles. The Large Eddy Simulation (LES) and Volume-of-Fluid (VOF) methods are applied as the turbulence model and multiphase model, respectively. The bubble behavior and flow field are analysed to reveal the mechanism of bubble separation. The predicted results show that there exists a funnel shape air gathering on the injection hole of water tank, and the air bubbles are separated from the upper part gradually. The separation behavior of air bubble results from the back flow induced by vortex structure. The strength difference of vortex in both sides is the major cause of zigzag motions of streamlines and bubbles.

Description: Siphon water conveyance is a commonly used way to transport water in high efficiency, and its core equipment is the submerged rectifying device at the entrance. Due to the complex structure inside the device, the local resistance loss is too high, which has a certain impact on the water delivery efficiency. By taking the single conical diffuser inside the siphon rectifying device as the research object, analyzing the mesh generation and the simulation strategy. Of which the target is reducing the resistance loss. Then the optimal plan is y w =10μm, N=20, R=1.3, using k-ε standard. And the analyzing of the head loss in each part of the conical diffuser is based on the simulation results. The obtained head loss of the diffuse part account for 40%-50% of the total loss. The parametric analysis of the conical diffuser structure is carried out for the diffuse part. Through the orthogonal design and the result analyzed, the optimal structural scheme is L1=36mm, L2=74mm, D1=17...

Description: The location of glacial lake is special and the results of previous researches are few. But it has caused a lot of geological disasters in its history, and been an urgent need to solve the engineering problems. Based on the historical data and a large number of field visits, the principle of the glacial lake disaster is analyzed, in combination with the first-hand data obtained from the site survey, the complexity of the glacial lake disaster mechanism is explained. It is believed that taking the glacier, glacial lake and the downstream rivers into consideration together is the key to solve the problem. This paper analyzes the possibility of glacial lake for hydropower generation, water diversion and water conservancy scenic area, and so on. On this basis, it proposes that the safety risk assessment is the basic work for disaster prevention and mitigation of glacial lake and their development and utilization.

Description: We analyse how oceanographic factors included sea surface temperature (SST), sea surface height anomaly (SSHA), and chlorophyll-a influence on small pelagic fish catches during El Niño Southern Oscillation (ENSO) event. The small pelagic fish catches and oceanographic factors derived from satellite imagery were analysed for the 5 years datasets (2010-2014). In this study, we demonstrate two species small pelagic fish consist of Eastern Little Tuna ( Euthynus affinis ) and Spanish Mackerel ( Scomberomorus commerson ) as representative of dominant catch in the west Java Sea. The results showed that Eastern Little Tuna and Spanish Mackerel catches had increment during El Niño than during La Niña, with an average catches of 839.6 t (Eastern Little Tuna) and 273,7 t (Spanish Mackerel) during El Niño event. The average catches during La Niña event were significantly decreased of 602.6 t (Eastern Little Tuna) and 210.3 t (Spanish Mackerel). Further analysis performs the habit...

Description: Remote Sensing, Vol. 10, Pages 1196: Evaluating the Best Spectral Indices for the Detection of Burn Scars at Several Post-Fire Dates in a Mountainous Region of Northwest Yunnan, China Remote Sensing doi: 10.3390/rs10081196 Authors: Davide Fornacca Guopeng Ren Wen Xiao Remote mountainous regions are among the Earth’s last remaining wild spots, hosting rare ecosystems and rich biodiversity. Because of access difficulties and low population density, baseline information about natural and human-induced disturbances in these regions is often limited or nonexistent. Landsat time series offer invaluable opportunities to reconstruct past land cover changes. However, the applicability of this approach strongly depends on the availability of good quality, cloud-free images, acquired at a regular time interval, which in mountainous regions are often difficult to find. The present study analyzed burn scar detection capabilities of 11 widely used spectral indices (SI) at 1 to 5 years after fire events in four dominant vegetation groups in a mountainous region of northwest Yunnan, China. To evaluate their performances, we used M-statistic as a burned-unburned class separability index, and we adapted an existing metric to quantify the SI residual burn signal at post-fire dates compared to the maximum severity recorded soon after the fire. Our results show that Normalized Burn Ratio (NBR) and Normalized Difference Moisture Index (NDMI) are always among the three best performers for the detection of burn scars starting 1 year after fire but not for the immediate post-fire assessment, where the Mid Infrared Burn Index, Burn Area Index, and Tasseled Cap Greenness were superior. Brightness and Wetness peculiar patterns revealed long-term effects of fire in vegetated land, suggesting their potential integration to assist other SI in burned area detection several years after the fire event. However, in general, class separability of most of the SI was poor after one growing season, due to the seasonal rains and the relatively fast regrowth rate of shrubs and grasses, confirming the difficulty of assessment in mountainous ecosystems. Our findings are meaningful for the selection of a suitable SI to integrate in burned area detection workflows, according to vegetation type and time lag between image acquisitions.

Description: Remote Sensing, Vol. 10, Pages 1192: Automating Parameter Learning for Classifying Terrestrial LiDAR Point Cloud Using 2D Land Cover Maps Remote Sensing doi: 10.3390/rs10081192 Authors: Chen-Chieh Feng Zhou Guo The automating classification of point clouds capturing urban scenes is critical for supporting applications that demand three-dimensional (3D) models. Achieving this goal, however, is met with challenges because of the varying densities of the point clouds and the complexity of the 3D data. In order to increase the level of automation in the point cloud classification, this study proposes a segment-based parameter learning method that incorporates a two-dimensional (2D) land cover map, in which a strategy of fusing the 2D land cover map and the 3D points is first adopted to create labelled samples, and a formalized procedure is then implemented to automatically learn the following parameters of point cloud classification: the optimal scale of the neighborhood for segmentation, optimal feature set, and the training classifier. It comprises four main steps, namely: (1) point cloud segmentation; (2) sample selection; (3) optimal feature set selection; and (4) point cloud classification. Three datasets containing the point cloud data were used in this study to validate the efficiency of the proposed method. The first two datasets cover two areas of the National University of Singapore (NUS) campus while the third dataset is a widely used benchmark point cloud dataset of Oakland, Pennsylvania. The classification parameters were learned from the first dataset consisting of a terrestrial laser-scanning data and a 2D land cover map, and were subsequently used to classify both of the NUS datasets. The evaluation of the classification results showed overall accuracies of 94.07% and 91.13%, respectively, indicating that the transition of the knowledge learned from one dataset to another was satisfactory. The classification of the Oakland dataset achieved an overall accuracy of 97.08%, which further verified the transferability of the proposed approach. An experiment of the point-based classification was also conducted on the first dataset and the result was compared to that of the segment-based classification. The evaluation revealed that the overall accuracy of the segment-based classification is indeed higher than that of the point-based classification, demonstrating the advantage of the segment-based approaches.

Description: Remote Sensing, Vol. 10, Pages 1197: Quantifying Drought Propagation from Soil Moisture to Vegetation Dynamics Using a Newly Developed Ecohydrological Land Reanalysis Remote Sensing doi: 10.3390/rs10081197 Authors: Yohei Sawada Despite the importance of the interaction between soil moisture and vegetation dynamics to understand the complex nature of drought, few land reanalyses explicitly simulate vegetation growth and senescence. In this study, I provide a new land reanalysis which explicitly simulates the interaction between sub-surface soil moisture and vegetation dynamics by the sequential assimilation of satellite microwave brightness temperature observations into a land surface model (LSM). Assimilating satellite microwave brightness temperature observations improves the skill of a LSM to simultaneously simulate soil moisture and the seasonal cycle of leaf area index (LAI). By analyzing soil moisture and LAI simulated by this new land reanalysis, I identify the drought events which significantly damage LAI on the climatological day-of-year of the LAI’s seasonal peak and quantify drought propagation from soil moisture to LAI in the global snow-free region. On average, soil moisture in the shallow soil layers (0–0.45 m) quickly recovers from the drought condition before the climatological day-of-year of the LAI’s seasonal peak while soil moisture in the deeper soil layer (1.05–2.05 m) and LAI recover from the drought condition approximately 100 days after the climatological day-of-year of the LAI’s seasonal peak.

Description: Due to its highly dynamic nature, coastal waters are necessary to be continuously monitor. Aerial wireless coastal buoy (AWCB) is one of the ocean instrument commonly deployed for observing oceanographic phenomena in coastal waters and around small islands. In this paper we describe the design, construction and the stability test result of new AWCB. The new AWCB is using water temperature sensors to collect data and transferring them through specific aerial wavelengths at real time and low cost in coastal areas. The AWCB is completed three steps. First, the buoy was designed using CAD software to determine its size, form and color. Next, the buoy was constructed using material from fiberglass. Last buoy was tested for its buoyancy and stability at the Acoustic and Instrument Laboratory, Faculty of Fisheries and Marine Sciences, Bogor Agricultural University. At sea-trial was also carried out around Pramuka Island, and during the trial it shows that the buoy is stable condition w...

Description: Rotating stall is a common unstable flow phenomenon in centrifugal pumps, which usuallyoccurs in part-load conditions. Rotating stall will cause performance instability when thepump is running, and even excite the resonance of the whole pump system in someextreme cases. In this paper, the stall phenomena at part-load conditions have beeninvestigated by CFDsimulation for a centrifugal pump. The CFD results have beencompared with the experiments, including characteristic curves, internal flow structures andcorresponding frequency spectrum analyses. Furthermore, a parameter named theblockage coefficient for the pump impeller passage is put forward to quantitativelyevaluate the magnitude of stall.The large-scale vortex in the stalled channel is defined as astall cell.At the operation condition Q=0.35Q 0 , five rotating stall cells can be observedin the impeller, which propagate among different impeller channels with a rotatingfrequency lower than that of the impeller. From ...

Description: the oscillation characteristics of pipeline pressure is an important factor affecting the operation stability of hydro turbine generating sets (HTGS), and is also the basis of the optimal control design of the HTGS. A nonlinear simulation model is established based on the Simulink, which is suitable to research the oscillation characteristics of pipeline pressure. The simulation model is verified by using the classic pipeline method of characteristic line (MOC). Simulating the guide blade disturbance signal by the Simulink module, the oscillation characteristics of pipeline pressure is simulated under different disturbance frequencies. The simulation results show that the natural period of the pipeline pressure oscillation is four times of the hydraulic pressure travel time, and the phase of the hydraulic pressure oscillation and the guide vane disturbance is opposite. Under a certain frequency of guide vane, the guide vane disturbance can significantly reduce the oscillation am...

Description: The analysis of hydraulic transient process is very important for the design and operation of pumped storage power (PSP) station. The one-dimensional mathematical model is often used in the transient process calculation, by which the maximum value at the spiral case inlet and minimum value at the draft tube inlet can be obtained. However, the one-dimensional mathematical model only provides cross section pressure trends at spiral case inlet and draft tube inlet, and the pressure fluctuation in load rejection cannot be revealed. But the pressure fluctuation amplitude of pump turbine in load rejection process is proved to be huge by test on site. In load rejection test, the measured pressure signals obtained from one or two taps, and the measured pressures affected by tap locations, and polluted by noise. So there exists great difference between the measured extreme values and numerical extreme values. To improve the accuracy of theoretical prediction, analysing the measured data ...

Description: The unsteady cavitating flows around a NACA66 hydrofoil with chord length 150 mm and the attack angle of 6 degrees was numerically simulated using two different turbulence models: the standard k-ε turbulence model and the PANS model. The results show that the standard k-ε turbulence model over predicts the eddy viscosity in the rear part of the cavity and fails to predict the unsteady shedding dynamics. However, it is found that the PANS model can accurately capture the general features of unsteady cavitating flow and the predicted shedding frequency agrees fairly well with the corresponding experimental data. Based on the predicted numerical results, the vorticity transport equation was implied to further analyze the strong interaction between the cavitation and vortex. The foundings in this study can provide further insight into the mechanism of cavitation shedding dynamics.

Description: An intake duct for a waterjet system is treated to improve the hydraulic efficiency and the outflow nonuniformity together with its perpendicularity. A multi-objective optimization strategy is proposed by incorporating with design of experiments (DOE), computational fluid dynamics (CFD), inverse design method, Kriging model and non-dominated sorting genetic algorithm-II (NSGA-II). Optimal Latin hyper-cube design method is used in DOE to uniformly sample in variation ranges, and global optimization is then conducted by using NSGA-II based on the input-target approximation functions approximated by the Kriging model. Instead of randomly selecting one solution to implement, a technique for ordering preferences by similarity to ideal solution (TOPSIS) is introduced to select the best compromise solution (BCS) from pareto-front sets. Compared with the original duct, the optimized intake duct has a much better outflow quality at the design operation point with a comparative hydraulic ...

Description: A trap device is defined as a closed structure which holds and provides a specific quantity of propellant using the surface tension forces. A trap in a vane-type PMD is investigated. The influence of the cone angle of the trap and flow distributions with different conditions in space are investigated. The VOF model could be used to simulate the flow distribution in a trap with zero or small gravity condition. The optimal angle for the trap is α=45° and it has the best result of expulsion efficiency of the propellant tank. The trap can be full filled with propellant after 21 second at zero gravity condition and 37 second at north-south insurance condition. A gas bubble left in the trap at the end of the refilling process. There is no flow distribution change in the trap when the trap is full filled at reverse gravity condition and sink condition.

Description: Floating ring bearings (FRBs) are widely used in the high speed turbocharger for their robustness. This paper introduces a CFD calculation method to predict the performance of the FRBs. Two phase model is included in the calculation method and transit calculation with mesh motion is conducted to predict the vibration characteristics. The simulation results are compared with the experiment to validate this method. Results show the two phase effect is important in predicting the FRBs at low oil-supplied pressure. This method shows great capacity of predicting the ring-to-shaft speed ratio and the vibration characteristics.

Description: Vertical self-priming pump has numerous advantages and has been widely used in industrial and agricultural areas. Nevertheless, impeller in single-stage self-priming pump bears large diameter and huge friction loss in the delivery of high-lift fluid, and enhanced requirement for sealing capacity meanwhile generates greater increment of power loss from sealing auxiliary-impeller and sealing ring. Both of these have resulted in low efficiency in operation, to the extent of imposing restriction on the further application of self-priming pump. In this paper, a new design of double-stage vertical self-priming pump with two impellers settled back to back was put forward to cover the shortfalls above. The internal flow field was calculated adopting realizable k-ε turbulence model in commercial CFD software Fluent and performance prediction was conducted. Concurrently, two-phase flow inside this self-priming pump without backflow hole was calculated by gas-liquid two-phase unsteady simu...

Description: In piping systems, hydrodynamic cavitation is well known for its destructive capabilities such as generation of intense noise. The investigation of the effect of the cavitation on acoustic pressure fluctuations and resonance frequencies provides much information about the geometry of the cavitation area, the propagation and the damping characteristics of the cavitation medium. The acoustical effects of cavitation caused by a water flow through a single-hole orifice have been investigated by using Computational Fluid Dynamics (CFD) and Ffowcs Williams–Hawkings (FW-H) formulation. The fluid zone downstream of the orifice where the cavitation happens considered as acoustic source. Time-accurate solutions of the flow-field variables are obtained from large eddy simulation (LES). Two cavitation regimes are investigated and for each regime, the sound pressure signals far downstream of the orifices are computed by applying the Ffowcs Williams–Hawkings (FW-H) formulation. From the resul...

Description: More attentions are paid to the renewable energies in face of global warming and depletion of fossil fuel. Tidal energy as one of the renewable energies has fruitful advantages as predictable and sustainable resources. The authors have proposed a counter-rotating type tidal stream power unit and investigated preliminarily the effect of the Reynolds number on the output, namely scale effect, and undersea noise of the counter-rotating propellers. The hydraulic loss increases at the low Reynolds number with accompanying the boundary layer separation. The noise has the dominant frequencies corresponding to the blade passing frequencies in counter-rotating propellers.

Description: Since the clearance between the runner shroud and the hub can change with the angle of the blades, it has a great influence on the hydraulic characteristics and cavitation performance in the Kaplan Turbine. In this paper, the CFD will be used to solve the turbulence model based on the k-ωSST model in the entire flow field of the turbine and the Zwart-Gerber-Belamri model will be used to predict the cavitation. We compare the hydraulic characteristics and cavitation performance of the Kaplan Turbine under the conditions of the runner clearance exist or the runner clearance absence. Finally, we analysis the influence of the clearance width in the hydraulic performance and the relationship between the clearances and the turbine characteristics.

Description: Focused on the unsteady behaviour of high-speed water jets with intensive cavitation a numerical analysis is performed by applying a compressible mixture flow method combined with a simplified bubble cavitation model. The mean flow of two-phase mixture is calculated by URANS for compressible flow and the intensity of cavitation in a local field is evaluated by the volume fraction of gas phase varying with the expansion and contraction of bubbles the mean flow field. High-speed submerged water jet issuing from a sheathed nozzle is treated when σ = 0.1 and Re = 4.5x10 5 . The distribution of cavitation clouds predicted approximately agrees with experiment data of visualization observation and the unsteady behaviour of cavitation cloud shedding is captured acceptably. Computational results reveal that cavitation occurs at the entrance of nozzle throat and bubble clouds expand and develop while flowing downstream along the boundary layer. Developed bubble clo...

Description: In order to analyze the vortex motion in the flow channel of the hydraulic turbine impeller during the gas volume fraction change. Now, the pump with a specific speed of 55.7 is chosen as hydraulic turbine. On the basis of considering the gas compressibility, to take numerical calculation on the model under different flow rates and different gas volume fraction, to analyze the influence of gas volume fraction on vortex motion law in the impeller flow channel. Findings: When the flow rate is small, the relative velocity distribution in the impeller flow channel is uneven, the velocity field is chaotic, and there are obvious vortices, with the increase of the gas volume fraction, the vortices in the impeller flow channel gradually move to the inlet direction of the blade; With the increase of the flow rate, the flow in the channel of the hydraulic turbine impeller is unstable. Both the pressure surface and the suction surface of the blade appear vortices, the vortex region in the ...

Description: Nowadays the frequency regulation of pumped-storage units becomes more and more important, due to the more complex structure of the grid and greater proportion of the renewable intermittent sources. The aim of this paper is to investigate the stability of pumped-storage plants (PSPs), and the subject of study is PSPs with surge tanks, shared water conduits and a common busbar. Firstly, the equations of each component in the system are deduced and simplified, to establish a linear time-invariant model by adopting the simplified transfer function (STF). A real Chinese PSP is taken as the engineering instance of this work, and simulation results of the STF model are validated with results of on-site measurements and computations based on the method of characteristics (MOC). Then, through both theoretical analysis and simulations, operating stability of the PSP system is studied under various islanded operating cases to reveal the influence of the hydraulic coupling and the electric...

Description: Hydraulic and structural performances are two main subjects in the optimization design of hydraulic machines. This article gives consideration to both hydraulic and structural performances during the optimization process of hydraulic turbine with main and splitter blades on the basis of Multidisciplinary Design Optimization (MDO). The aim is to improve the optimization methods of hydraulic turbine, shorten the development cycle time and ensure stable and efficient operation of the unit. Computational fluid dynamics(CFD) and finite element method(FEM) analysis are combined to improve the overall performance of the runner in the multidisciplinary optimization process. The optimization considers the whole runner including the crown and band to get more accurate results of stress distribution. Open Grip program was used to parameterize runner blade and Bezier curve was used to match the bone line and it changed the blades through transforming the bone lines of different profile. NSG...

Description: In order to understand the flow pattern of salt-out particles in a bittern transfer pump, the population balance model (PBM) coupled with mixture two-phase was applied to calculate the particle flow. User-defined particle growth and nucleation models were used in this study to consider the actual dynamic behavior of the crystallization particle, such as particle growth, nucleation, aggregation and breakage. The result shows that the average particle size is smaller and more evenly distributed among area of the impeller inlet. The size of crystal particles is different at different regions in the impeller passages with the characteristics of small crystal particles near suction side and large crystal particles near pressure side. In addition, the distribution of average particle size near pressure and suction side has an upward trend from inlet to outlet. The distribution of crystal particles on the blade near the tongue is different from other blades whether it is in the pressur...

Description: Based on a multistage gas-liquid centrifugal pump as the research object, considering the buoyancy and surface tension of gas at the same time, the N - S equations and the standard two equations k - ε turbulent model were used for the numerical simulation of triple-stage pump of different gas content, the external characteristics and the internal flow field of the pump were analyzed. The results indicated that with the increasing of gas content, the head and efficiency of the pump were reduced, and the decrease rate increases with the increase of the gas content. Under the action of centrifugal force, the gas phase in the impeller mainly gathers near the hub. In this paper, the method of opening the return hole was used to optimize the pump, and the modification was calculated by steady numerical simulation. By analyzing the pump liquid velocity distribution, the axial force and the performance of the pump, to provide the basis for optimizing the performa...

Description: In order to investigate the effect of rotational speed on hydraulic performance of inlet and outlet conduits for S-shaped shaft extension tubular pumping system, the three dimensional steady turbulent flow in pumping system was simulated using computational fluid dynamics technology. The experiment results are compared with the CFD results. The hydraulic performance parameters of inlet and outlet conduits were analyzed quantitatively considering the hydraulic interaction of conduits and impeller. The change trend of relationship curves between hydraulic loss ratio value and flow rate coefficient is same in different rotational speed. With the increase of flow rate coefficient, the hydraulic loss ratio value increases gradually, the hydraulic efficiency increases firstly then decreases gradually, and the average velocity circulation of outlet section increases firstly then decreases gradually in the same rotational speed. With the increase of rotational speed, the average velocit...

Description: The paper deals with the influence of the tongue shape on the flow characteristics at the near-tongue region of the volute in the double suction centrifugal pump with long-tongue, middle-tongue and short-tongue respectively. For this study, the computational fluid domains including suction chamber, impeller and volute was simulated by means of the commercial CFD software that solved the Navier-Stokes equations for three-dimensional steady flow. The results show that the tongue shape has a significant impact on the pump head and efficiency in a range of 0.4Q d -1.4Q d flow rate. Under small flow conditions, the head and efficiency of the short-tongue model are higher than that of the middle-tongue model and long-tongue model. Under large flow conditions, the head and efficiency curves of the three models are relatively close. In addition, the tongue shape has a great influence on the pressure and the streamline distribution in the near-tongue region. Therefore,...

Description: Pelton turbine is widely used in in utilizing the high water head resource. The multiphase flow in the Pelton turbine is too complex to be analysed detailed as the flow in the reaction turbines. So the hydraulic design of Pelton turbine was mainly based on the know-how. The homologous turbine model was the only way to verify its performance in the past. Although an efficiency scale-up equation for Pelton turbines had established in the IEC 60193 code, researches had shown different internal flow phenomena would influence the efficiency scale effects and lead to different efficiency scale for different turbine design. This paper simulates the internal flow of model and homologous prototype Pelton turbine at three relative needle strokes. Homogenous model and SST k - ω model will be adopted to simulate the unsteady two-phase flow in the rotating buckets. Unsteady simulation results would help to numerical investigate the scale effect of Pelton turbine.

Description: Lancang Island is the center of fisheries of blue swimming crab in Kepulauan Seribu, Jakarta. Most of the inhabitants in this island are fishermen, and blue swimming crab is the main target without considering the stocks. One of the management effort of blue swimming crab by the government is the restriction of catchment size. To support the government policy and to maintain the population stocks and the sustainability of blue swimming crab around Lancang Island, we need another effort such us proposing area of Marine Sanctuary. The analysis of possibility area of the marine sanctuary was performed with simulated annealing using Marxan. The datasets were used in analysis included geomorphic model of habitat (sea floor), coastal ecosystems, blue swimming crab catches (sample size, location, and fishing pressure). The results obtained three possibility locations of the marine sanctuary, which is around of Laki Island, Southern, and Southeastern of Lancang Island. From the possibil...

Description: Red tide is a common phenomenon and almost present every year in Lampung Bay. In 2012, the red tide in Lampung Bay showed a different characteristic compared to the previous ones. The research was conducted to analyze the characteristics of organisms causing the red tide and the factors affecting its occurrence. Assessments were done by identifying the dominant phytoplankton and observing the environmental condition using rapid assessment method. Seawater sampling was conducted in 15 stations in December 2012 to monitor the phytoplankton abundance, nutrient, and physical condition. The results showed that the organism dominating the phytoplankton population is Cochlodinium sp., comprising of 85.89% of the total phytoplankton suggesting it was the red tide organism in the Bay. The average abundance of this species in the stations was 2.0 × 10 4 cells/L. Choclodinium sp. was present agglomerated and distributed along the west coast of the bay. The highest co...

Description: The analytical investigation of the rotor dynamics system in large vertical volute pump is presented in this paper. The radial force imposed on impeller is a time-independent value which is extracted from the numerical simulation results. A three-dimensional finite element analysis of the pump rotor was performed to investigate the critical speed and mode shape. The transient response of the rotor dynamics is studied by analysing radial excitation force at variable flow conditions. In addition, the stiffness and damping of the bearings are calculated by Software ARMD. The result shows that the resonance of pump will not occur under design condition. The radial displacement of monitoring point at impeller presents periodic variation when the time-independent radial force is imposed on impeller.

Description: Flow-induced vibration is a prevailing phenomenon in the operation of the hydraulic machinery system. Fluid-structure interaction (FSI) is an important characteristic of flow-induced vibration and must be taken into account in design phase of hydraulic machinery. FSI in the form of mass loading and damping, it has a major impact on the dynamic response of the structural. Hydrodynamic damping can reduce the vibration amplitude and improve the stability of the hydraulic machinery which is of great importance. The aim of this study is to prediction the hydrodynamic damping characteristics of a NACA 0009 hydrofoil by using three dimensional two-way fluid-structure interaction modeling. The first bending mode of the hydrofoil is excited to produce the deformation, then the deformation information is transmitted to the flow field through the fluid-solid coupling junction. In the numerical simulation, dynamic response is acquired by dynamic mesh deformation of flow field, and the hydro...

Description: Despite the fact that hydropower development provides great opportunities, it also comes with complex challenges and risks that differ considerably by the type, place, and scale of projects. Sub-Saharan African has had a long and successful experience in the operation of large hydropower. Hydropower provides the highest % in total electricity generated in the Region. However, hydropower development has slowed. Today, various Governments in the Region are taking renewed interest in the development of hydropower of all sizes, comprising small hydropower, which is realized to be a national resource that can be developed by local entrepreneurs, with least environmental and social impact. This presentation is to add to the discussion on how to establish agenda for elevation of economically, socially and environmentally viable small hydropower development in Sub-Saharan African. The following important issues and challenges are discussed in this document thus; the potential of small h...

Description: The Indonesian Throughflow passing through the Halmahera Sea (H-ITF) is supposed to be supplied by the western boundary current system, particularly from the New Guinea Coastal Current (NGCC). However, characteristics of H-ITF and NGCC is not well understood yet. This paper aims to investigate vertical structure, transport volume estimate, and transport variability of H-ITF and its coherency with NGCC in the upper 200 m depth. The dataset are obtained from daily INDESO model output (2008-2014). H-ITF across latitude of 0.3°S is indicated by a strong intensified southward flow in upper 150 m with 67.2 km width, and mean transport volume 2.35 (±1.94) Sv (southward). Furthermore, NGCC across 134°E is characterized with 291.2 km width, strong velocity core (〉0.4 m/s) in the upper 200 m depth, and transport volume 13.47 (±6.6) Sv (westward). The model indicated that H-ITF is supplied by 17.45% of NGCC. Variability of H-ITF is dominated by intraseasonal period. High coherence (0.85...