•A digital hydrostatic drive solution for large utility wind turbine was proposed.•Two digital encoding schemes for a 2.5 MW hydrostatic wind turbine were developed.•A digital hydrostatic wind ...turbine control based on kw2 control law was proposed.•Digital hydrostatic solution improves energy production of hydraulic wind turbine.
Gearbox failure is one of the major factors causing the increased downtime in modern wind turbines. This increases the turbine maintenance cost and therefore the turbine cost of energy. A hydrostatic transmission not only improves the turbine reliability through its “soft” transmission, but also eliminates the use of power converter through its continuous variable transmission function. A hydrostatic wind turbine usually employs a fixed displacement pump to drive a variable displacement motor. The variable displacement motor runs at partial displacement when the wind speed is below the rated wind speed, leading to low drivetrain efficiency. Moreover, large variable displacement motors for large utility wind turbine are not commercially available. Therefore in this paper a digital hydrostatic transmission solution for large utility wind turbine has been proposed. The large variable displacement motor was replaced by combining several fixed displacement motors and a small variable displacement motor with some digital encoding scheme. Two encoding schemes have been proposed for digital hydrostatic transmission. The modeling and design of the digital hydrostatic wind turbine were presented. A hydrostatic wind turbine control based on kw2 control law has been proposed. A dynamic simulation model of the digital hydrostatic wind turbine has been developed. The proposed digital hydrostatic drive solution has been compared with a conventional hydrostatic solution in a commercial 2.5 MW wind turbine. Simulation studies verified the feasibility and the engineering practice of the proposed digital hydrostatic drive solution.
Most of the present deep‐atmosphere models are based on finite‐difference schemes. This article proposes a novel deep‐atmosphere non‐hydrostatic spectral dynamical kernel with hydrostatic‐pressure ...based terrain‐following vertical coordinate. Contrary to finite‐difference methods, a spectral transform method is used for the horizontal discretization. The prognostic variables in our dynamical kernel are analogous to the typical ALADIN‐NH spectral model. A two time level semi‐implicit semi‐Lagrangian time‐stepping scheme is applied to enable large time steps and improve the efficiency of integration. A set of test cases are conducted to evaluate the accuracy and stability of the deep‐atmosphere dynamic kernel.
Deep‐atmosphere steady‐state test case for normal Earth (X = 1). Results are plotted (from top to bottom) at (a, b) day 0 (initial states), and (c, d) day 10, showing (a, c) temperature and (b, d) zonal wind.
The efficacy of regional climate model RegCM4.6 using hydrostatic core resolutions at 36km (HY36) and 12km (HY12) and a non‐hydrostatic core resolution at 12km (NH12) is investigated by simulating ...the normal, excess and deficit monsoon seasons. The ERA‐Interim reanalysis data are used to drive the model and the India Meteorological Department (IMD) and modern‐era retrospective analysis for research and applications (MERRA) rainfall data are used for precipitation verification. The heavy rainfall regions are well simulated in the high‐ compared with the coarse‐resolution simulations, with the maximum in the NH12. The non‐hydrostatic dynamics amalgamate the vertical acceleration with the orographic uplifting that causes more precipitation over hilly regions than that of the hydrostatic core. On the other hand, the lesser precipitation over northwest India is better portrayed in the HY12 than in the other two. Over central India, the HY36 performs better followed by the NH12; and the contrasting precipitation features are also well depicted in the HY36 and NH12. This is probably because of the better representation of large‐scale monsoon features, such as a monsoon trough in the HY36 and local‐scale convective activities in the NH12. Daily rainfall analysis also shows that the high‐resolution model is capable of capturing the active and break phases during the El Niño and La Niña seasons. The non‐hydrostatic model possesses good correlation co‐efficients >0.5 over the hydrostatic model with co‐efficients of 0.35. The analysis of upper air circulations and the derived parameters, including statistical tests, confirm that the RegCM4.6 with non‐hydrostatics is useful for orographic regions, hydrostatic at a coarse resolution and non‐hydrostatic at a finer resolution and could be suitable for plain regions.
Model domain and elevation (masl) used in the present study.
We address the questions: are the temperature and thermodynamic pressure significantly different for thermodynamic equilibrium under hydrostatic versus non-hydrostatic stresses? Moreover, is the ...nature of the equilibrium state comprising the number of phases and their microstructure different? Only closed thermodynamic systems are considered involving both fluid present and fluid absent mineral reactions. Distinctions are drawn between hydrostatic, fluid, mechanical and thermodynamic pressures. The thermodynamic pressure is always equal to the mechanical pressure (the mean stress) for a linear elastic material but differs from the mechanical pressure if processes involving dissipative volume changes operate. The fundamental principle governing equilibrium in a crystalline aggregate under a non-hydrostatic stress at a given temperature and mean stress is that the elastic energy be minimised. This can be attained in a vast number of ways that involve changes in chemical composition and crystalline structure, as in the growth of garnet on biotite, subtle changes in chemical composition, as in a solid solution series or an order–disorder transition, microstructural rearrangements, as in subgrain formation, and combinations of all of these as in myrmekite formation. All involve changes in the elastic energy of the system and force a new conceptual approach to the definition of a phase and a phase diagram. A microstructural phase rule needs to be considered in conjunction with a mineral phase diagram. For practical purposes the thermodynamic pressure generally is close to the mean stress. A chemical potential for a stressed solid can always be defined if diffusive processes operate. For solid/fluid systems the difference in conditions defining equilibrium for hydrostatic and non-hydrostatic conditions is a second order effect; multiple equilibrium states can exist. Departures from hydrostatic conditions are marked by the form of the phase rule (that is, the topology of the phase diagram) and hence there must be either changes in the Clapeyron slope or the position of the equilibrium phase boundary unless all the modifications to the phase rule are achieved by microstructural rearrangements and subtle changes in chemical composition. For solid/solid systems the shift in equilibrium conditions for non-hydrostatic stresses can, in principle, be very large but such effects can be mitigated by softening of the elastic moduli at phase transitions and are also limited by the difference between the mean stress and the equilibrium hydrostatic pressure. For natural situations the difference between the non-hydrostatic and hydrostatic equilibrium temperature is not likely to exceed 20K. For non-hydrostatic conditions if soft mode nucleation and growth processes dominate, departures from hydrostatic conditions are again marked by changes in the form of the phase rule. Departures in the phase rule from hydrostatic conditions in both fluid present and fluid absent reactions are expressed as variations in chemical composition and differences in the number of phases and their microstructural arrangements at equilibrium under non-hydrostatic as opposed to hydrostatic conditions. The types of microstructures expected at equilibrium under non-hydrostatic conditions include those well documented as arising from internal “spontaneous” stresses in crystals as well as distinct new mineral phases. If the couplings between elastic lattice distortions and diffusive processes, or plastic deformation, are strong then softening modes are suppressed or enhanced and large departures from the hydrostatic Clapeyron slope are possible.
The current study focuses on the RegCM4.5 model and specifically on a comparison of hydrostatic and non‐hydrostatic approaches as well as on different microphysical parameterisations and planetary ...boundary layer (PBL) schemes. The main goal of the paper is to simulate the historical regional precipitation characteristics of the Carpathian region as reliably as possible. For this purpose, seven different model experiments at a 10 km horizontal resolution were completed for a 10‐year period (1981–1990) using ERA‐Interim reanalysis data (with 0.75° resolution) as initial and boundary conditions. Our simulation matrix consists of hydrostatic and non‐hydrostatic runs together with different treatments of moisture, namely, the SUBEX and the NogTom schemes. In addition, two PBL schemes are tested, the Holtslag and the UW‐PBL scheme. In this detailed validation study, RegCM outputs (e.g., temperature, global radiation, cloud cover, precipitation) are compared to the homogenized, gridded CarpatClim data (available with 0.1° resolution) that are based on measurements at regular meteorological station sites. The validation considers seasonal and monthly means, as well as extreme climatic events. On the basis of the results we can conclude that the role of the non‐hydrostatic core can be clearly recognized for precipitation, particularly over mountains. Moreover, it was also found that the UW‐PBL scheme performs with a negative bias regarding atmospheric boundary layer thickness and temperature and it reduces the wet/dry biases of the Holtslag PBL scheme. Regarding microphysical schemes, the NogTom scheme performs better than the SUBEX scheme, but the modified SUBEX (SUB4.3) can also reduce the precipitation over mountainous areas.
The current study focuses on analyses of evaluating the impact of different dynamical core (hydrostatic and non‐hydrostatic) and parameterization schemes (such as large‐scale precipitation scheme and planetary boundary layer scheme) on model performance over Carpathian region. The results show the PBL scheme has a substantial effect on the temperature, while the non‐hydrostatic core and large‐scale precipitation schemes can clearly be recognized for precipitation.
This review focuses on describing and discussing recent findings regarding the effects of high hydrostatic pressure (HHP) on the supramolecular structure and technofunctional properties of starch, as ...well as on analyzing the hypothesis to explain these changes. The non-thermal modification of starch through HHP involves complex supramolecular structural changes that depend on the botanical source, amylose content, and treatment intensity. Overall, the granular morphology, lamellar and crystalline structures, and double helices undergo different degrees of modification/disorganization during HHP, but these changes are distinguished from thermal modification by an improvement at the same gelatinization degree. The HHP-induced supramolecular modifications determine the properties of starch, including water solubility, swelling power, pasting, water and oil holding capacity, thermal properties, and in vitro digestibility.
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Fishery products are delicious, nutritional and healthy foods, and their popularity in today's market is growing. With the changes in consumer consumption expectations as well as the development of ...reliable cold-chains, fresh preprocessed fishery products such as fillets are more popular with consumers and producers because of their convenience for processing and cooking. However, fishery products after being removed from water have a short shelf life due to their intrinsic characteristics. Therefore, developing effective preservation technology to extend postmortem shelf life of fishery products has been an on-going area of study. This review summarizes the patterns of quality deterioration and external factors that affect postmortem quality of fishery products, and then updates the recent advances with preservation methods for fishery products including superchilling, modified atmosphere packaging, active packaging, edible coatings, irradiation and high hydrostatic pressure. Moreover, the advantages and disadvantages of each technology are discussed, and future trends for improving the preservation of fishery products are also discussed.
•Effect of pressure on digestibility of common buckwheat starch (CBS) was studied.•High hydrostatic pressure (HHP) significantly increased amylose content in CBS.•HHP significantly decreased rapidly ...digested starch, starch hydrolysis and viscosity.•HHP elevated slowly digested starch, resistant starch and improved thermostability.•HHP also significantly decreased the textural properties of CBS.
High hydrostatic pressure (HHP), a non-thermal processing technology, was applied at 120, 240, 360, 480, and 600MPa to assess its effect on the in vitro digestibility, physicochemical, and structural properties of common buckwheat starch (CBS). HHP treatment resulted in CBS granules with more rough surfaces. With the increasing pressure level, amylose content, pasting temperature, and thermal stability substantially increased and relative crystallinity, hardness, swelling power, and viscosity decreased. At 120–480MPa, HHP did not affect the ‘A’-type crystalline pattern of CBS. However, at 600MPa, HHP contributed to a similar ‘B’-type pattern. Compared with native starch, HHP-modified CBS samples had lower in vitro hydrolysis, reduced content of rapidly digestible starch, and increased levels of slowly digestible starch and resistant starch. These results revealed that the in vitro digestibility, physicochemical, and structural properties of CBS are effectively modified by HHP.
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•WPI gel particles induced by high hydrostatic pressure were prepared and characterized.•Pickering emulsions and emulsion gels stabilized by the particles were attained.•The particles ...had potential to stabilize high internal phase emulsion gels.•The curcumin-loaded Pickering emulsion gels were fabricated and evaluated.
In this study, whey protein isolate (WPI) gel particles were fabricated via high hydrostatic pressure (HHP) treatment and homogenization and the potential of using the particles as food-grade stabilizers to form Pickering emulsions and emulsion gels were studied. The result showed that pH had a significant effect on the properties of WPI gel particles. In the pH range near the isoelectric point (pI) (around pH 5.0), the particles exhibited spherical structure with larger size. The droplet size, creaming stability, microstructure and rheological properties of the Pickering emulsions stabilized by the WPI gel particles were influenced by pH and ionic strength, particle concentration and oil fraction. Pickering emulsion gels were formed from the Pickering emulsions stabilized by the particles at pH 5.0 after storage for 3 days at room temperature (25 °C). Confocal laser scanning microscopy (CLSM) demonstrated that the WPI gel particles formed a densely packed particle layer on the surface of oil droplet, suggesting the potential of these particles as Pickering emulsion stabilizers. Besides, the Pickering emulsion gels had the highest loading efficiency of curcumin and best stability against light degradation.
•HHP slightly influenced the biochemical composition of oysters.•The PUFA profile was higher in steamed oysters than raw and HHP samples.•The EUC in raw oysters was the highest, followed by HHP and ...steamed oysters.•The major organic acid in raw and HHP oysters was succinic acid.•The contents of inorganic ions were higher in raw and HHP oysters than steamed group.
In this study, the effects of high hydrostatic pressure (HHP) and steam on biochemical composition and non-volatile taste active compounds of oysters Crassostrea hongkongensis were investigated. The moisture content in steamed oysters significantly decreased when compared to raw samples, subsequently their crude protein, crude lipid, glycogen and ash contents (% wet weight) were all increased (P < 0.05). In addition, though the moisture content in HHP oysters decreased, no significant differences were observed in proximate compositions compared to raw oysters, except crude protein. There were no significant differences in saturated fatty acids (SFA), monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) profiles between raw and HHP oysters, however, C20:3n6 content in HHP oysters was significantly higher than that in raw samples (P < 0.05). The PUFA profile of steamed oysters, mostly contributed by n-3 PUFA, was significantly higher than that of both raw and HHP samples (P < 0.05). Major free amino acids (FAA) (taste activity value, TAV > 1) in oysters with three treatments were alanine, glycine, glutamic acid and histidine, and their contents were significantly higher in raw and HHP groups than that in steamed group. The 5′-inosine monophosphate (IMP) and 5′-guanosine monophosphate (GMP) in HHP and steamed oysters decreased compared to raw samples, while AMP content in steam oysters were significantly increased (P < 0.05). The equivalent umami concentration (EUC) of oysters of raw, HHP and steamed groups were 8.80, 3.66 and 1.44 g MSG/100 g, respectively, with significant differences observed among different treatments (P < 0.05). Succinic acid was the major organic acid in raw and HHP oysters, while lactic acid was the major organic acid in steamed groups. Further, Na+, K+, PO43− and Cl− were the main inorganic ions (TAV > 1), and their contents were significantly higher in raw and HHP groups than that in steamed group (P < 0.05). This study demonstrated that HHP treatment slightly influenced the changes in the biochemical composition and non-volatile taste active compounds to raw oysters, compared to steamed process.
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