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This study investigates the impact of financial inclusion in bringing the financing gap of water infrastructure in developing countries using Togo as case study. Using a number of robust estimation techniques, we found that financial inclusion is associated with an increase in access to improved drinking water and a decline in the travel time to the water source, especially among the rural poor areas, female heads households and the northern part of the country. The influence of formal inclusive finance is higher and significant in contrast to informal financial inclusiveness, which has no significant impact. Policy implications are discussed. [ABSTRACT FROM AUTHOR]

Lv et al. ([9]) investigated the risk factors influencing WRCC of China based on risk theory and resources carrying capacity theory and proposed a method for the risk assessment of the WRCC by combing the vulnerability and the hazard of WRCC system. Three papers explained water resource carrying capacity (WRCC) with different spatial scales at the city, region, and national levels using different methods. Lee and Lee ([6]) investigated shared benefits through the cooperation between North Korea and China over transboundary water management in the Yalu River Basin. Closing remarks to the featured collection: Water security - New technologies, strategies, policies, and institutions. [Extracted from the article]

Water reclamation and reuse are an important means to alleviate the shortage of water resources. This paper proposes several different decision‐making models to investigate what different participants in industrial water recycling, including users, suppliers, and local governments, should do in different situations. In the models, different decision logics of the participants about water reclamation are presented. Finally, the models are used in a case study and some meaningful results are obtained. The study explains the gap between the relatively low utilization and the strong demand for water recycling. Research Impact Statement: There are presented the decision‐making models of industrial water recycling. Cooperation between reclaimed water user and expertized supplier can create surplus value. [ABSTRACT FROM AUTHOR]

A streamline curvature method based integrated throughflow analysis approach is newly developed to deal with component matching problems of variable cycle compression systems. The construction of variable cycle compression system is modularly modelled in the procedure. Splitting and confluent flow are elaborately disposed. A numerical method based on the "streamline floating" character of streamline curvature method is developed to model the function of forward variable area bypass injector. Moreover, extensive models used in the throughflow calculations, including minimum loss incidence, deviation and loss models were assessed, selected and modified. Finally, code validations were conducted on three representative traditional compressors, i. e. NASA rotor 67, NASA stage 37 and a custom-designed low-speed repeating four-stage compressor. Both the predicted overall characteristics and spanwise profiles agree reasonably well with the experimental data. The validated procedure was finally used to sketch the performance maps of a double bypass compression system under two different control rules, i. e. the first bypass throttling and the second bypass throttling. The results show some aspects of the difficulties and complications in operating a variable cycle compression system, and meanwhile, demonstrate the superiority of the newly developed integrated throughflow method. [ABSTRACT FROM AUTHOR]

This article analyses the electromagnetic performance of dc-biased current vernier reluctance machines (DCB-VRMs) with distributed windings. Taking example of 12-stator slot machines, the coil connection and current configuration are illustrated. Moreover, the back electromotive force (EMF), torque capability, etc., are analyzed by finite-element analysis (FEA). In addition, the torque density of DCB-VRMs equipped with distributed and nonoverlapping windings are compared. The results show that some combinations of distributed winding machines present a higher torque capability thanks to the higher pole ratio. [ABSTRACT FROM AUTHOR]

High-speed machines exhibit the advantages of super-high-power density, high efficiency, etc. and have been gaining more research attention in recent years. This article proposes an elaborate high-speed vernier reluctance machine (HSVRM) topology. The main advantages are as follows: (1) the stator adopts the so-called half-quasi-squirrel cage winding so that one side of all conductors is short connected and the other side is powered by modular inverter, (2) dc-biased current is fed into each conductor independently so that the machine can operate with the principle of magnetic field modulation, and (3) ladder rotor is equipped to weaken the torque ripple of the machine. Obviously, the machine topology significantly resolves the shortage of overlong end length and improves the fault-tolerant ability. In this article, the basic principle and electromagnetic characteristics of the machine will be analyzed by finite element analysis (FEA). [ABSTRACT FROM AUTHOR]

This article proposes a novel two-phase dc-biased current Vernier reluctance machine (DCBVRM) equipped with concentrated windings. Compared with the existing three-phase DCBVRMs, the number of power electronic switching devices has been greatly reduced without sacrificing performance. Consequently, the overall system cost is greatly reduced, and thus, it is competitive for low-cost applications such as household appliances. To highlight the advantages of the proposed topology, the theories of coil connection, current configuration, and so on are illustrated, and some electromagnetic characteristics, such as flux density, back electromotive force, and electromagnetic torque, are predicted by finite-element analysis (FEA) with two eight-stator slot machines. Finally, the comparison with three-phase counterpart shows that the proposed eight stator slots, seven rotor slots, and two-phase machine can exhibit 21% higher torque with much lower inverter cost. [ABSTRACT FROM AUTHOR]

• First study generated naturalized streamflow and assesses environmental flow for all tributaries of the Amudarya River. • The estimated environmental flow ranged from 25 to 46% of naturalized mean annual flow (MAF) for all tributaries. • Current environmental flow (2–5% of MAF) is extremely lower than the estimated one for the delta region. • Environmental conditions are severely damaged in the middle and lower reaches. The Amudarya River (ADR) is the largest source of freshwater in Central Asia providing livelihood to millions of people by extracting water for agriculture. However, the over-exploitation has created some critical environmental issues. For example, almost no water for the delta and the Aral Sea, which was once the 4th largest lake in the world. The present study focused on the assessment of environmental flow requirements (E-flows) in the basin. However, the main challenges in the accomplishment were the unavailability of natural streamflow, which is necessary for E-flow assessment, and sparse and limited hydroclimatic data. A hydrologic model was configured to simulate naturalized streamflow using the meteorological data from the Climate Research Unit. Four hydrological methods (i.e., Tennant, low flow index (7Q 10), flow duration curve analysis (Q 90 , and Q 95), and flow duration curve shifting (FDCS)) and all-method mean were applied to estimate E-flows at 34 sites on all tributaries of the ADR. According to FDCS, 7Q 10 , Q 90 , and Q 95 , E-flows should be 46%, 37%, 30%, and 25% of naturalized mean annual flow (NMAF), respectively, and on average, it should be 35% of NMAF, assessed by the all-methods mean. For low-flow (October–March) and high-flow (April–September) months, E-flows were determined to be 20–30% and 40–98% of NMAF, respectively. E-flow evaluation with the current environmental conditions showed very serious concerns because no sites met the environmental flow requirements below Kerki. This study will be guidelines to improve the riverine ecosystem and for future sustainable development in the region. [ABSTRACT FROM AUTHOR]

Urban water governance in China has received increasing academic and policy attention owing to frequent urban water crises. Drawing on documentary analysis and field investigations, this article analyzes the administrative system and recent policy developments vis-à-vis urban water governance in China. It demonstrates the main problems of, and mechanisms for, interdepartmental and interjurisdictional coordination, and reviews new policy instruments addressing urgent urban water governance issues. The article argues that coordination mechanisms such as the river chief system are promising but their long-term effectiveness remains to be clarified, and more attention should be paid to policy enforcement and market mechanisms. [ABSTRACT FROM AUTHOR]

Since the founding of the People's Republic of China in 1949, great achievements have been made by China in all aspects of water governance. Besides water conservancy projects, a water resources management system with Chinese characteristics has also been completed. In this article, we summarize the achievements of the past 70 years in flood control, soil and water conservation and water supply, and introduce the water governance institutions of China that sustain those achievements. This provides valuable experience and ideas for other countries that are suffering from similar water issues. [ABSTRACT FROM AUTHOR]

China's water stress and its pressure on food security is a widely recognized crisis. A framework is proposed and applied at the provincial level to evaluate China's water security for food production. It is based on a water stress index that accounts for the deficit between water supply and aggregate demand of 23 major field crops over the study period (1961–2015). The water demand is estimated based on method recommended by the Food and Agriculture Organization of the United Nations. The water supply is composed of rainfall and irrigation. Consequently, the water security of both rainfed and irrigated agriculture is evaluated in our research, and the respective contribution of rainfall and irrigation is distinguished. Suggestions regarding adjustment in irrigation investment and planting area are proposed for practical application. The framework also holds great potential to investigate the impact of climate change and the virtual water flow of crops. Plain Language Summary: With 7% of the world's arable land and 6% of its water resources, China has to feed 20% of the world's population. Consequently, China's water stress and its pressure on food security is a widely recognized crisis. A framework is proposed in our research to evaluate China's water security for food production. It is mainly designed to answer the following three questions critical to China's food security but have not been systematically addressed in the literature. How much water is required under China's current agriculture planting structure? What is the respective role of rainfall and irrigation in meeting this requirement? What is the status of water security for China's rainfed and irrigated agriculture? The above three questions are answered based on a water stress index that accounts for the deficit between water supply and aggregate demand of 23 major field crops over the study period (1961–2015). We have also proposed suggestions regarding water security for food production from the framework. For future use, our proposed framework lays the groundwork to investigate the virtual water flow of crops. Climate change signals can also be incorporated into this framework to inform climate‐driven water risk for agriculture. Key Points: A new framework is proposed to evaluate water security for food productionRespective contribution of rainfall and irrigation to water security is distinguishedSpatial patterns of China's water security for food production are investigated [ABSTRACT FROM AUTHOR]

Zinc‐ion batteries (ZIBs) are a promising alternative for large‐scale energy storage due to their advantages of environmental protection, low cost, and intrinsic safety. However, the utilization of their full potential is still hindered by the sluggish electrode reaction kinetics, poor structural stability, severe Zn dendrite growth, and narrow electrochemical stability window of the whole battery. Graphene‐based materials with excellent physicochemical properties hold great promise for addressing the above challenges foe ZIBs. In this review, the energy storage mechanisms and challenges faced by ZIBs are first discussed. Key issues and recent progress in design strategies for graphene‐based materials in optimizing the electrochemical performance of ZIBs (anode, cathode, electrolyte, separator and current collector) are then discussed. Finally, some potential challenges and future research directions of graphene‐based materials in high‐performance ZIBs are proposed for practical applications. [ABSTRACT FROM AUTHOR]

In the 1960s, Lake Chad (LC) was one of the largest inland water body on the earth and since then, it has extremely shrunk from a surface area of 25,000 km2 to 2000 km2. The present study determines hydro-climatic changes in the active parts of the Lake Chad basin by using trend analysis and the causes of declining stream flow to LC due to human interventions and climate variability by using a hydrological approach. One approach, which is used to estimate changes in stream flow due to climate variability, is also modified in this study. Trend results showed that mean temperature exhibited very strong increasing trends, with a mean rise of 1.4 °C for 1951–2015, while precipitation presented very weak to strong declining trends, with an overall decline of 15%. Regarding stream flow, all major rivers showed very strong downward trends, resulting in 67% decline. The northern and eastern regions were the most impacted areas in the basin regarding decreasing precipitation and increasing temperature. The hydrological approach showed that decreasing stream flow to LC varied between 34% and 45% in different decades. In general, human activities attributed a 66% decline in stream flow and climate variability 34% for the impacted period (1972–2013) relative to 1951–1971. Only during 1982–1991, climate variability caused most reduction (59% of total) in stream flow because of devastating drought during this period. Since stream flow to LC was mostly affected by human activities, proper water resources planning and sustainable management are necessary but under the umbrella of considering changing climate. Unlabelled Image • Impacts of climate variability and human activities were assessed using hydrologic approach. • Human activities caused more reduction (66%) in inflow to Lake Chad than climate variability. • Climate variability was assesses using Mann-Kendal and Sen's slope methods. • Highly significant increasing trends were observed, with an increase of 1.4 °C/65 yrs. • Moderate signals of decreasing trends were explored, with decline of 15%/65 yrs. [ABSTRACT FROM AUTHOR]

Highlights • Water loss of the Chari River discharge is evaluated using a statistical approach. • The contribution of climate variability and human activities is distinguished. • Previously the contribution of human activities has been underestimated seriously. Abstract Lake Chad was once the sixth largest lake in the world, with a surface area of about 25,000 km2 in the early 1960s. However, it has shrunk to almost only one-twentieth of its maximum area by now. As the biggest river of the Lake Chad basin, the Chari/Logone River contributes approximately 90% of Lake Chad's water input. Consequently, several previous studies have focused on the Chari/Logone River system to investigate the causes of Lake Chad's shrinkage. However, due to the lack of authoritative irrigation and natural runoff observations, it is usually difficult to explain the relative contribution of human activities and climate variability. In this paper, unlike the hydrological modeling approaches used in previous studies, a conceptual and statistical approach was presented to investigate discharge variations and the causes leading to such variations. Specifically, the runoff change caused by climate variability (Δ Q climate ) was estimated using Budyko analysis, while that caused by human activities (Δ Q human ) was estimated using regression analysis. The accuracy of estimation was evaluated through cross validation and comparison with previous studies. The comparison suggests that due to the lack of natural runoff and irrigation withdrawal observations, the runoff simulation produced by previous hydrological models suffers from large errors. The water loss of the Chari/Logone River discharge is dominated by human activities rather than climate variability. On annual average scale, the total water loss caused by climate variability and anthropogenic activities is 16.76 km3. The relative contribution of Δ Q climate and Δ Q human is 26.83% and 73.17%, respectively. The role of human activities is particularly obvious in recent ten years from 2003 to 2013. Due to the increase of rainfall and irrigation withdrawals, the relative contribution of human activities accounts for more than 80% of the total water loss. [ABSTRACT FROM AUTHOR]

The recent novel dc-biased sinusoidal current reluctance machines (dc-biased VRMs) adopt a doubly salient structure and concentrated windings, which is similar to that of switched reluctance machines (SRMs). The special point is that the phase current is in the form of an ac component superimposed with a dc component. Some literary works show that these machines would have better performance than the existing SRMs and variable flux reluctance machines. In this paper, the slot/pole combinations and winding configurations of the dc-biased VRMs are deeply investigated. First, relationships among slots/poles are given based on the operation principles. Then, several feasible slot combinations are obtained, and the electromagnetic performances including magnetizing inductance, virtual back electromotive force, torque quality, and losses are compared by the finite element analysis. Finally, the correctness of the proposed analysis is validated by the experiment on two 12/10 prototypes. [ABSTRACT FROM AUTHOR]

This paper addresses the design and investigation of an improved torque density dc-biased Vernier reluctance machine (dc-biased-VRM), which is characterized by salient rotor structure, and merely one set of concentrated windings in stator. First, a 12-stator slot, 10-rotor slot dc-biased-VRM is designed. Then by analyzing the magnetic flux distribution with finite-element analysis, it is found that the flux always doesn’t flow across half of the stator teeth. Therefore, these teeth are removed and a novel 6/10 dc-biased-VRM with 20% higher torque density is obtained. Besides, by optimizing the stator/rotor tooth width combination and tooth shape, the torque ripple is lowered. Finally, a prototype is manufactured and experimental results show good agreement that is observed between the simulation and test data for the proposed motor. [ABSTRACT FROM AUTHOR]

DC-biased sinusoidal current vernier reluctance machines (dc-biased VRMs) have a doubly salient structure, and their phase currents contain an alternating current (ac) component and a direct current (dc) component. Hence, their main features are one set of concentrated windings compared with variable flux reluctance machines, low vibration and noise due to smooth current, compared with switched reluctance machines, and robust rotor structure. Besides, its achievable high slot fill factor can improve the torque density further. In this paper, based on the flux modulation principles, the torque production mechanism of dc-biased VRMs is analyzed, and two slot combinations of 12/8 and 12/10 are proposed. First, the machine topology and inverter main circuit are illustrated. Second, the torque production mechanism is explained. Furthermore, the inductance characteristic, optimal current configuration for maximum torque and lowest torque ripple are analyzed theoretically and by the finite-element analysis. Finally, one prototype was designed and built, and the proposed analysis is validated by the experimental results. [ABSTRACT FROM AUTHOR]

Stator permanent magnet (PM) machines are gaining more research interest in recent decades. Since the permanent magnets (PMs) are moved from the rotor side to the stator side and the salient rotor structure is adopted, it is claimed that the stator permanent magnet machines exhibit several promising features, such as simple and robust rotor, and good ability of heat dissipation as the main losses are located in the stator. On the other hand, to improve the shortcomings of the inherent limited magnetic field adjustment ability, and the low efficiency and power factor of stator dc current excited machines, hybrid excitation PM machines with additional field windings are proposed. However, the complexity of the machine structure is increased inevitably. At present, it is found that both the stator PM and the stator dc current excited Vernier machines operate with the flux modulation principle, and generally, the armature windings of the stator PM machines are fed with pure sinusoidal current. In this paper, a novel hybrid excitation stator PM Vernier machine is analyzed. In addition to the features of the salient rotor structure, stator located PMs, and concentrated armature windings, the novelty of this machine is dc-biased sinusoidal phase current, which contains an ac component and a dc component. The fundamental theories of stator PM machines fed with dc-biased current are researched, operation principle and slot/pole combination is concluded, and the optimal current configuration is studied theoretically and by finite element analysis. Finally, a prototype was designed and manufactured; the experimental tests were done to validate the proposed analysis. [ABSTRACT FROM AUTHOR]

In this study, the linear scaling method used for the downscaling of temperature was extended from monthly scaling factors to daily scaling factors (SFs) to improve the daily variations in the corrected temperature. In the original linear scaling (OLS), mean monthly SFs are used to correct the future data, but mean daily SFs are used to correct the future data in the extended linear scaling (ELS) method. The proposed method was evaluated in the Jhelum River basin for the period 1986-2000, using the observed maximum temperature (Tmax) and minimum temperature (Tmin) of 18 climate stations and the simulated Tmax and Tmin of five global climate models (GCMs) (GFDL-ESM2G, NorESM1-ME, HadGEM2-ES, MIROC5, and CanESM2), and the method was also compared with OLS to observe the improvement. Before the evaluation of ELS, these GCMs were also evaluated using their raw data against the observed data for the same period (1986-2000). Four statistical indicators, i.e., error in mean, error in standard deviation, root mean square error, and correlation coefficient, were used for the evaluation process. The evaluation results with GCMs' raw data showed that GFDL-ESM2G and MIROC5 performed better than other GCMs according to all the indicators but with unsatisfactory results that confine their direct application in the basin. Nevertheless, after the correction with ELS, a noticeable improvement was observed in all the indicators except correlation coefficient because this method only adjusts (corrects) the magnitude. It was also noticed that the daily variations of the observed data were better captured by the corrected data with ELS than OLS. Finally, the ELS method was applied for the downscaling of five GCMs' Tmax and Tmin for the period of 2041-2070 under RCP8.5 in the Jhelum basin. The results showed that the basin would face hotter climate in the future relative to the present climate, which may result in increasing water requirements in public, industrial, and agriculture sectors; change in the hydrological cycle and monsoon pattern; and lack of glaciers in the basin. [ABSTRACT FROM AUTHOR]

This study presents indexes developed from remote sensing observations for continuous soil surface moisture monitoring. The Modified Temperature Vegetation Dryness Index (MTVDI) proposed in our earlier work is developed using a time domain solution method rather than the traditional spatial domain solution method, because of limitations arising from a traditional temperature-vegetation index (TVX) method. In the procedure herein proposed, the MTVDI parameterization scheme is transformed from regional scale to pixel scale, and the boundary conditions defining maximum water stress are determined pixel by pixel using the surface energy balance principle. All the parameters required for the retrieval of MTVDI are pixel specific, thereby avoiding the limitations of the traditional spatial domain solution method. Previous studies demonstrate the applicability of the TVX method with data from only a few days of clear sky conditions. In contrast, our proposed MTVDI is demonstrated using Moderate Resolution Imaging Spectroradiometer (MODIS) products over the course of a full year, and the soil moisture status over the Southern Great Plains (SGP) region is monitored continuously. Finally, the volumetric surface soil water content ( θ v ) is estimated using a calibration procedure from the MTVDI retrievals. The results show that the accuracy of both MTVDI retrievals and θ v estimates obtained in this work has reached a level comparable with those produced in previous studies. Across all sites, the correlation coefficient ( r ) between the MTVDI and θ v measurements is 0.60. The values of r , mean absolute error ( MAE ) and root mean square error ( RMSE ) for θ v estimates are 0.75, 0.019 m 3 m − 3 and 0.025 m 3 m − 3 , respectively. [ABSTRACT FROM AUTHOR]

The contextual surface temperature-vegetation index (TVX) models have been widely used for the retrieval of soil moisture (SM) and evapotranspiration (ET). One of the key premises for their application is to determine quantitatively the theoretical boundaries of this contextual TVX space. Usually these theoretical boundaries are determined based on land surface energy balance principle. Although sound in physical mechanism, the complex parameterization involved has hampered its remote sensing (RS) applications. Our recent studies show that ground-based SM observations can be used for a quick and continuous retrieval of these theoretical boundaries. The main disadvantage lies in its reliance on in-situ SM observations. Fortunately the development of microwave RS technology has made it possible to monitor SM at both regional and global scale. Under this background, a practical framework based on the contextual TVX models was proposed in this paper for continuous ET estimation through the combination of microwave-based SM products and MODIS (Moderate Resolution Imaging Spectroradiometer) products. Daily actual ET over the Southern Great Plains of the United States of America was calculated as the product of net radiation and evaporative fraction (EF). The focus of this framework was to investigate how optical and microwave RS can be combined to achieve a quick and continuous retrieval of EF independently of ground observations. Specifically, EF was retrieved from the contextual TVX models, the theoretical boundaries of which were calibrated at the annual scale based on an optimization scheme. Assuming the seasonal variation of the theoretical dry edge follows a cosine function of solar zenith, the essence of this optimization scheme is to search for the optimal amplitude parameter that maximizes the correlation between microwave-based SM observations and soil moisture index retrieved from the contextual TVX models. Two microwave-based SM products including SMAP (Soil Moisture Active Passive) and SMOS (Soil Moisture and Ocean Salinity) were adopted to demonstrate this optimization scheme. The correlation coefficient, root mean square error and bias of EF estimates calibrated by SMAP were 0.700, 0.146 and 0.047, and those achieved by SMOS were 0.663, 0.174 and 0.168, respectively. The optimization scheme has not only made it possible to conduct a continuous monitoring of ET based entirely on RS observations but also achieved the downscaling of microwave satellite SM products. Thus the combination of optical and microwave RS holds great potential for coupled and continuous estimation of SM and ET over large scale. [ABSTRACT FROM AUTHOR]

This paper proposes a novel hybrid excitation vernier permanent magnet machine (HE-VPM). The characteristics of the proposed machine are: 1) the PMs are embedded in the stator teeth, which is helpful for the heat dissipation; 2) the rotor is salient structure without PMs and windings, which ensures the reliability of high-speed operation; 3) the nonoverlapping concentrated winding shortens the end-connection, and improves the torque density, 4) only half of the stator teeth possess PMs, and the total amount of PMs are decreased; and 5) the dc current are injected to the armature coils, therefore, the exciting field can be adjusted flexibly. In this paper, the electromagnetic performance, including back electromotive force, torque, etc. are analyzed with finite element analysis. The results show that the proposed machine exhibits flexible field adjustment capability, which may be suitable for applications requiring wide speed range operation. Besides, it is found that, compared with the existing pure sinusoidal phase current, higher torque density can be obtained with dc-biased phase current under constant stator copper loss. [ABSTRACT FROM AUTHOR]

Recently, stator dc current excited vernier reluctance machines (dc-VRMs) which have concentrated field and armature windings in stator, are gaining more and more research interest due to their features of robustness rotor structure, low cost, and easy heat dissipation. This paper proposes a novel field winding connection for dc-VRMs. Taking the stator/rotor slots of 12/10 machine as an example, the electromagnetic performance including back electromotive force (EMF), pulsating torque, and capability are analyzed using the theoretical and finite element analysis. The results show that compared with the previous machine having the same stator/rotor slots, machine with the proposed field winding connections exhibits a doubling back EMF, and 60% higher torque density. [ABSTRACT FROM AUTHOR]

Flux modulated machine (FMM) comprises three parts: a conventional stator with armature winding, a rotor with permanent magnet, and iron flux modulation pole. Thanks to the inherent magnetic gearing effect, FMMs have been gaining more attention for their features of high torque density. So far, the windings of existing FMMs are fed with pure sinusoidal current. In this paper, to further improve the torque density using the magnetic gear principle, dc-biased sinusoidal current is innovatively injected into the armature coils which are arranged in a specific way, and the electromagnetic performance is analyzed by the finite element analysis. The results show that the electromagnetic torque contains not only the preexisting PM torque, but also the additional torque produced by the dc current interacted with the ac armature current. What is more, it is found that with the proposed dc-biased current, the torque density is improved under the constant copper loss compared with the existing pure sinusoidal current. Besides, the flux adjustment ability is greatly enhanced since the exciting field can be easily adjusted by the injected dc current. [ABSTRACT FROM AUTHOR]

Stator dc field winding excited vernier reluctance machines are increasingly attracting research interest recently due to their low cost and highly reliable rotor structure. In this paper, the design of these machines is studied systematically using both theoretical equations and finite element analysis (FEA). First, the general structures of these machines and their operation principles are discussed. Second, based on the operation principle, the back electromotive force, torque, and power factor expressions are deduced in terms of the geometrical variables. Several key design parameters are defined, including stator/rotor slot/pole combinations, air gap, split ratio, field/armature coil turn ratio, and stator/rotor tooth arc combination. Third, the deduced theoretical expressions are verified by the FEA. Finally, a prototype is designed and tested to verify the analysis results. [ABSTRACT FROM PUBLISHER]

Since the concept of virtual water was put forward, there has been an increasing number of papers on the topic, as a result of which virtual water is now being mainstreamed in the water policy world. Unfortunately, virtual water trade strategy as a solution to water shortages is wrong and fallacious. Although the virtual water trade theory is considered a descendant of the comparative advantage theory of economics, it is in fact an over-simplification, going from the truth to fallacy. To make decisions of virtual water trade based on only one production factor, water, though there are many other production factors that influence the allocation of resources at the same time, is misleading theoretically and practically. [ABSTRACT FROM AUTHOR]

Stator dc winding excited Vernier reluctance machines (DC-VRMs) are one novel kind of Vernier reluctance machines, and have doubly salient structure and additional dc field windings in their stators to generate the exciting field. These machines advantages include a wide speed range, due to the flexible exciting field by the dc winding and a robust rotor structure without permanent magnets or windings. In this paper, the nature and principles of DC-VRMs are first illustrated theoretically with winding function and harmonic theories. First, by considering the permeance modulation function, the equations and harmonics of the exciting field are obtained. Next, based on these results, the stator/rotor pole combinations and armature winding configuration methods are proposed. Additionally, the expressions for the self-inductance, mutual inductance, the back electromotive force (back-EMF) of armature windings are summarized with the winding function theories. Also, the effects of permeance, field, and armature winding harmonics on inductance harmonics are analyzed. The equation for electromagnetic torque is also given, and the design parameters that may influence the machine's torque are provided. Finally, the inductances and torque in synchronous reference frame are analyzed. All the analytical results are validated by finite element analyses and some experimental results are also given to validate the theoretical analysis. [ABSTRACT FROM PUBLISHER]

Direct-drive permanent magnet (PM) synchronous generators (DDPMSGs) are gaining more and more attention and application for wind power. This paper presents a comprehensive performance comparison of an external rotor surface-mounted PM synchronous generator equipped with three commonly used winding types, i.e., integral-slot distributed winding (ISDW), fractional-slot concentrated winding (FSCW), and fractional-slot distributed winding. The tradeoff between torque and the power factor, loss distribution, current, torque, and PM demagnetization characteristics under a short-circuit fault and the steady temperature rise are investigated and compared using finite-element analyses. It is found that, generally, FSCW PM generators exhibit high rotor losses compared with ISDWs, which will lead to an overly high temperature rise. Measures such as segment PMs and the adoption of lamination steel in the rotor can reduce the rotor loss and greatly improve the machine efficiency. However, the temperature rise of FSCW machines is still higher than that of ISDW machines. The conclusion is intended to help choose the proper winding types. [ABSTRACT FROM AUTHOR]

Stator dc-excited vernier reluctance machines (dc-VRMs) are a kind of a novel vernier reluctance synchronous machine that employs doubly salient structures; their innovations include stator concentrated dc windings to generate the exciting field. Compared with the rotor wound field machines or stator/rotor PM synchronous machines, these machines are characterized by low cost due to the absence of PMs, a robust rotor structure, and a wide speed range resulting from the flexible stator dc exciting field. In this paper, with the proposed phasor diagram, the power factor of dc-VRMs is analyzed analytically and with the finite-element analysis, and the analysis results are confirmed with the experiment. It is found that, with constant slot sizes and slot fill, the power factor is mainly dependent on the ratio of the dc current to the armature winding current and also the ratio of the armature synchronous inductance to the mutual inductance between the field winding and the armature winding. However, torque will be sacrificed if measures are taken to further improve the power factor. [ABSTRACT FROM AUTHOR]

As the operating temperature of the motor increases, the material properties will be seriously affected, such as soft magnetic materials, hard magnetic materials, and winding insulation properties. For high-speed permanent magnet motors, the higher loss density and smaller heat dissipation area make the impact of temperature more serious. However, according to the test standard, the magnetic properties are usually measured at room temperature, ignoring the effect of temperature. To accurately design magnetic devices, it is necessary to understand the behavior of magnetic materials at different temperatures. In this article, a new high-speed permanent magnet claw-pole motor with soft magnetic composite for a wide temperature range is proposed. The design process mainly includes the calculation and analysis of material temperature characteristics, bearing support, topological structure, rotor stress calculation, and so on. Finally, a prototype is manufactured and tested to verify the design process. [ABSTRACT FROM AUTHOR]

The article offers the author's insights regarding the article "Less Water, More Grain in Dry Hebei Province, China," by her, Z. Ge and X. Fang that was published in the 2011 issue of the journal "Water International." She mentions a letter from Doctor Chris Perry pointing that the article was an example of failure to do proper traditional water accounting. She explains why they use water use instead of water consumption to calculate water productivity.

Abstract: The availability of precipitation data with high spatial resolution is of fundamental importance in several applications such as hydrology, meteorology and ecology. At present, there are mainly two sources of precipitation estimates: raingauge stations and remote sensing technology. However, a large number of studies demonstrated that traditional point measurements based on raingauge stations cannot reflect the spatial variation of precipitation effectively, especially in ungauged basins. The technology of remote sensing has greatly improved the quality of precipitation observations and produced reasonably high resolution gridded precipitation fields. These products, derived from satellites, have been widely used in various parts of the world. However, when applied to local basins and regions, the spatial resolution of these products is too coarse. In this paper, we present a statistical downscaling algorithm based on the relationships between precipitation and other environmental factors in the Qaidam Basin such as topography and vegetation, which was developed for downscaling the spatial precipitation fields of these remote sensing products. This algorithm is demonstrated with the Tropical Rainfall Measuring Mission (TRMM) 3B43 dataset, the Digital Elevation Model (DEM) from the Shuttle Radar Topography Mission (SRTM) and SPOT VEGETATION. The statistical relationship among precipitation, DEM and Normalized Difference Vegetation Index (NDVI), which is a proxy for vegetation, is variable at different scales; therefore, a multiple linear regression model was established under four different scales (0.25°, 0.50°, 0.75° and 1.00°, respectively). By applying a downscaling methodology, TRMM 3B43 0.25°×0.25° precipitation fields were downscaled to 1×1km pixel precipitation for each year from 1999 to 2009. On the basis of three criteria, these four downscaled results were compared with each other and the regression model established at the resolution of 0.50° was selected as the final downscaling algorithm in this study. The final downscaled results were validated by applying the observations for a duration of 11years obtained from six raingauge stations in the Qaidam Basin. These results indicated that the downscaled result effectively captured the trends in inter-annual variability and the magnitude of annual precipitation with the coefficient of determination r 2 ranging from 0.72 to 0.96 at six different raingauge stations. [Copyright &y& Elsevier]

Correlation analysis and a water productivity indicator are used to investigate the inverse relationship between increasing grain output and declining irrigation water use in Hebei Province, People's Republic of China, especially since 2003. A rapid improvement in water productivity more than offset the decline in available water even in one of the most water-stressed areas of north China. As long as this trend continues, there is little need for concern about a grain production crisis induced by water shortage. [ABSTRACT FROM PUBLISHER]

This paper presents a detailed analysis of the long-term relationship between China's grain output and its use of irrigation water. It shows that over the last 30 years, China has maintained an increase in grain output while irrigation water withdrawal has been decreasing. Irrigation water use was not significantly correlated with grain output due to the greater offsetting effect of prices and cropping area. Although China's agricultural water use will continue to dwindle, there is no reason to expect that water productivity increases cannot continue to keep pace. This is no excuse for complacency, however. [ABSTRACT FROM AUTHOR]

High speed becomes an important development direction of permanent magnet synchronous machines (PMSM) for higher power density. However, with the reduction of the switching-to-fundamental frequency ratios (SFRs), the dynamic performance and robustness of the current controller deteriorate and even lead to instability. To address this issue, this article proposes a distinctive current controller designed directly in the discrete-time domain for PMSM, which combines two-degree-of-freedom internal model control (TDOF-IMC) with active damping. The salient feature of this controller is that from the point of directly assigning or optimizing the pole and zero coordinates, a distinctive current controller is designed. Specifically, the TDOF-IMC realizes the ability to arbitrarily arrange the pole–zero placement of the closed-loop transfer function, and, therefore, the current tracking response can be improved. The addition of active damping enhances the antidisturbance ability, and as a result, the dq-axis current oscillations effectively at low SFR are getting weakened. On this basis, current control can achieve better dynamic response and robustness at the same time. Finally, simulation and experimental results validate the effectiveness of the proposed controller. [ABSTRACT FROM AUTHOR]

Ground-based evaporative fraction (EF) observations have been used widely for validation purposes in previous remote sensing-based EF models. Few studies have investigated whether such measurements can be utilized for calibration use. In this paper, an observation-driven optimization method is proposed to quantify EF over a large heterogeneous area within the surface temperature-vegetation index framework. It is designed at both daily scale and seasonal scale with MODIS products and in-situ EF observations over the Southern Great Plains in the US. The goal is to search for the optimal dry edge within the allowable range that minimizes the difference between the estimated and observed EF of a given site. Results show that the accuracy produced using only one site for calibration has reached a level comparable to those produced by traditional triangle methods. Compared with the daily-scale optimization method, the seasonal-scale optimization method has not only demonstrated its superiority in accuracy but also held distinctive advantages over the traditional triangle methods. Specifically, the dry edge produced by our optimization method holds true under both clear sky and partially cloudy conditions. This has not only bypassed the repetitive work of previous triangle methods but also made it possible to conduct a continuous monitoring of EF. Besides, the optimization method is characterized by its simplicity in algorithm, stability in accuracy and extensibility in parameterization, which makes it a suitable tool for providing a quick and reasonable estimation of EF over large heterogeneous areas from a limited number of in-situ EF observations. • An optimization method is proposed to calibrate RS-based EF models. • Accuracy produced using one site for calibration has reached an acceptable level. • The method has the capacity to provide a quick and continuous monitoring of EF. • The method is also characterized by its simplicity, stability and extensibility. [ABSTRACT FROM AUTHOR]

The three rivers' source region (TRSR) located in the Qinghai-Tibetan Plateau is an important ecological region of China for its location and high elevation. However, the ecological condition of the region is critical to water conservation and ecological security in China. Therefore, the present study focused on determining the environmental flow requirements (EFRs) of the Lancang (above Xiangda streamflow gauge), Yangtze (Zhimenda), and Yellow (Tangnaihai) Rivers, which will be helpful in the sustainable development of the region. Because of lacking ecological data, we used four hydrological methods (i.e., flow duration curve shifting, Tennant, flow duration curve analysis, and low flow index method) to assess the EFRs for the minimum and optimum eco-environmental conditions of these rivers. Since there was missing data on most gauges and we had streamflow data of only one gauge (Zhimenda) in the Yangtze headwater region, a hydrological model was applied to complete the missing data and simulate the streamflow data for the Tuotuo, DamChu, Chumar, and Tongtian Rivers for the estimation of the EFRs insides the region. The environmental flows of 118 m3/s (76% of mean annual flow, MAF), 312 m3/s (72% of MAF), 484 m3/s (77% of MAF) were determined for the conservation of the optimum riverine ecosystem and 67 m3/s (43% of MAF), 155 m3/s (36% of MAF), and 290 m3/s (47% of MAF) for the minimum eco-environmental conditions for the Lancang, Yangtze, Yellow Rivers, respectively. It was also noticed that low flow months (November to April) required more proportions of mean monthly flow than high flow months (May to October). These preliminary results will be very supportive of the water resources managers and policymakers in the case of any sustainable socio-economic development in the region. Unlabelled Image • Environmental flows were assessed in the headwater regions of the Yangtze, Yellow and Lancang Rivers. • HEC-HMS was applied to simulate discharge in main tributaries of Yangtze River. • 70–78% of mean annual flow was explored as optimal environmental flow requirements. • 30–47% of mean annual flow was explored as the minimum environmental flow requirements. • Low flow months requires more proportions of mean annual flow than high flow months. [ABSTRACT FROM AUTHOR]

An understanding of climate variability, trends, and prediction for better water resource management and planning in a basin is very important. Since the water resources of the Lake Chad basin (LCB) are highly vulnerable to changing climate, in the present study, a combination of trend analysis methods was used to examine the climate variability and trends for the period of 1951–2015 using observed and Climate Research Unit (CRU) data, and a combination of spectral analysis techniques was used for the prediction of temperature and precipitation using CRU data. Eighty-four percent of the temperature time series indicated extremely strong signals of increasing trends (α = 0.001) and 25–38% of the precipitation time series indicated strong decreasing trends (α = 0.05). Temperature is expected to increase and precipitation is expected to decrease in the future. However, surprisingly, in some regions located in the South, the temperature was predicted to decrease slightly in 2021–2030 relative to 2006–2015. This decrease might occur because these regions are highly protected natural resource areas and forests are frequently present. On the whole, the temperature was predicted to increase by 0.65–1.6 °C and precipitation was predicted to decrease by 13–11% in the next two decades (i.e., 2016–2025 and 2026–2035) relative to 1961–1990. Periodic analysis showed a 20- to 25-year cycle in precipitation in all basins and a 40- to 45-year cycle in temperature but only in the Chari-Logone basin. [ABSTRACT FROM AUTHOR]

In this study, a linear scaling method, precipitation extended linear scaling (PELS), is proposed to correct precipitation simulated by GCMs. In this method, monthly scaling factors were extended to daily scaling factors (DSFs) to improve the daily variation in precipitation. In addition, DSFs were also checked for outliers and smoothed with a smoothing filter to reduce the effect of noisy DSFs before correcting the GCM’s precipitation. This method was evaluated using the observed precipitation of 21 climate stations and five GCMs in the Jhelum River basin, Pakistan and India, for the period of 1986–2000 and also compared with the original linear scaling (OLS) method. The evaluation results showed substantial improvement in the corrected GCM precipitation, especially in case of mean and standard deviation values. Although PELS and OLS showed comparable results, the overall performance of PELS was better than OLS. After Evaluation, PELS was applied to the future precipitation from five GCMs for the period of 2041–2070 under RCP8.5 and RCP2.6 in the Jhelum basin, and the future changes in precipitation were calculated with respect to 1971–2000. According to average all GCMs, annual precipitation was projected to decrease by 4% and 6% in the basin under RCP8.5 and RCP2.6, respectively. Although two seasons, spring and fall, showed some increasing precipitation, the monsoon season showed severe decrease in precipitation, with 22% (RCP8.5) and 29% (RCP2.6), and even more reduction in July and August, up to 34% (RCP8.5) and 36% (RCP2.6). This means if the climate of the world follows the RCP8.5 and RCP2.6, then there will be a severe reduction in precipitation in the Jhelum basin during peak months. It was also observed that decline in precipitation was higher under RCP2.6 than RCP8.5. [ABSTRACT FROM AUTHOR]

A definition of water security is that it is the sustainable availability of water of adequate quantity and quality for a particular use, whether for humans or the environment. Water security is arguably one of the top global water issues. Management strategies, policies, and institutional guidelines to address water security and governance issues, sustainable access to adequate quantities of and acceptable quality water; and 7. [Extracted from the article]

This article takes 12-slot/10-pole axial flux permanent magnet (PM) synchronous machine (AFPMSM) with fractional-slot concentrated windings and yokeless and armature (YASA) topology as the research object. Winding magnetomotive force (MMF) of three-phase double-layer layout is analyzed by three kinds of methods, which are star diagram method, winding function method, and holographic spectrum method. The analysis results of finite-element method (FEM) show that the three methods are effective and consistent in analyzing winding MMF. Comparative analysis of iron loss density and B–H magnetizing curves of four typical iron materials are studied. B–H hysteresis loops of silicon steel sheet and soft magnetic composite are measured by magnetizing and measuring equipment to validate iron core per unit mass. The three-dimensional FEM is used for analyzing eddy-current loss in PMs considering radial segmentation. Finally, an AFPMSM prototype is manufactured adopting YASA topology and segmented PM. Load experiments show that solid–liquid coupling computational fluid dynamics model can precisely predict temperature distribution of AFPMSM. Improved cooling jacket is beneficial to afford large current load. [ABSTRACT FROM AUTHOR]

A Coupled Infrastructure Systems perspective is applied to three cases in north-western China to explain how and why water rights systems and water markets have changed since 1949. The evolution of water rights systems has been shaped by periods of water-supply projects and periods that emphasized regulatory and institutional measures to manage water resources. We argue that water supply infrastructure and water markets have been developed not in sequence but in parallel. The development of water diversion projects and nationwide market-oriented water allocation reform programmes will continue to co-evolve in the future as part of complex coupled infrastructure systems. [ABSTRACT FROM AUTHOR]

Assessment of historical evolution of groundwater levels is essential for understanding the anthropogenic impact on groundwater exploitation and developing response policies. In this study, regional groundwater level trend was addressed based on the regional Kendall test with correlated spatial data. With a limited number of data at one location, an exponential relation was proposed to be used to approximate covariances of a variable as a function of distances between locations. The effectiveness of the method was demonstrated using synthetic data experiments. The regional Kendall method was applied to assess evolution of groundwater levels and their annual decline rates in Beijing, Tianjin, and Hebei in China based on county‐level data in 1959, 1984, 2005, and 2013. Results indicated that a continuing declining regional trend was shown in groundwater levels, revealing generally higher groundwater recharge rates than withdrawal rates in the study region. The annual groundwater decline rates presented a firstly increasing then decreasing regional trend, which is consistent with the environmental Kuznets curve. The earlier accelerating groundwater decline rate was attributed to supply‐driven water resources management, whereas the reversed trend in accelerating groundwater decline rate in the latter period was due to many measures implemented to relieve local water stresses. Article impact statement: Regional Kendall test is adapted and applied. Results indicate Environmental Kuznets curve in groundwater level decline rate in case study. [ABSTRACT FROM AUTHOR]

The effects of multi-phase and multi-layer windings of the 12-slots 10-poles surface-mounted permanent magnet synchronous machines (SPMSMs) on eddy current losses in permanent magnets (PMs) are mainly investigated using the 3-D finite element analysis in this paper. Eddy current losses in PMs considering its axial segmentation are also analyzed. It is demonstrated that dual three-phase four-layer (DTP-FL) winding layout has the minimum value of eddy current losses in PMs, when segmentation number $N = 4$. It is because DTP-FL winding has smaller magnitude of high-order magnetomotive force harmonics relative to other four winding layouts. The average torque and torque ripple changing with multi-phase, multi-layer, and axial segmentation are also studied. Finally, the no-load and load experiment platform for an axial flux integrated-starter generator with DTP-FL winding and radial segmented PM are established in order to validate the proposed method under power generation mode. [ABSTRACT FROM AUTHOR]

It is well known that remote sensing techniques hold the potential to explore the spatial estimation of air temperature ( T a ) with fine spatial and temporal resolution across the world. However, because of the complex interaction of land-atmosphere system and the contamination of cloud cover, the retrieval of daytime T a exclusively from remote sensing data is still far from straight forward, especially under cloudy sky conditions. In this paper, we presented a simple parameterization scheme of daytime T a under all-weather conditions entirely based on Moderate Resolution Imaging Spectroradiometer (MODIS) products. To evaluate its applicability, the scheme was demonstrated in two regions with totally different geomorphological and climatic conditions, the east part of the Qaidam Basin (EQB) in China and the Southern Great Plains (SGP) in the United States of America. The instantaneous T a under clear sky conditions ( T a , clear ) was determined as the average of near surface air temperature ( T a S ) retrieved from MOD07_L2 product and land surface temperature ( T s ) retrieved from MOD06_L2 product. Then a regression model between T a , clear and T s was established, and the instantaneous T a under cloudy sky conditions ( T a , cl oudy ) was estimated by applying the regression model to T s retrieved under cloudy sky conditions. The results showed that the averaging parameterization scheme has significantly improved the accuracy of T a , clear retrievals with MAE = 1.95 °C, RMSE = 2.50 °C, and B = 0.02 in the EQB, and MAE = 2.02 °C, RMSE = 2.56 °C, and B = 0.01 in the SGP. The T a , cloudy estimates also showed good agreement with T a observations in both regions with a correlation coefficient ( r ) higher than 0.91. The values of RMSE calculated for the EQB and SGP were 3.42 °C and 2.91 °C, respectively. The accuracy of both T a , clear and T a , cloudy estimates has reached a level comparable with other traditional statistical approaches that adopt ancillary T a measurements as training dataset. Therefore, it is feasible to estimate daytime T a under all-weather conditions entirely based on MODIS products. [ABSTRACT FROM AUTHOR]

This article employs the case of the Yellow River basin to advance understanding of the water–energy–food nexus by demonstrating how the country’s energy and agriculture sectors are competing for limited water supplies and by quantifying the future water demands in the two sectors. The results show that in 2030 the water demands for food and energy are likely to increase by less than 4 km3and 1 km3, respectively, in the Yellow River basin. The analysis suggests that agricultural water savings and inter-basin water transfers are the main ways to ensure sufficient water flows through the basin to fulfil demand for both sectors while preserving the natural ecosystems. [ABSTRACT FROM PUBLISHER]

[Display omitted] • A remote sensing-based method is proposed for daily ET mapping and partitioning. • This method is applied to a poorly gauged basin in the Qinghai-Tibet Plateau. • ET in Qaidam Basin is estimated and partitioned continuously over twenty years. • Its ET features in different landscapes as well as their controls are identified. Accurate estimation and partitioning of terrestrial evapotranspiration (ET) is essential for understanding the hydrological cycle and water use efficiency at different scales. Such knowledge is particularly important for sustainable water resources management in arid ecosystems. A daily scale framework for continuous ET mapping and partitioning was proposed in this study based on a universal solution of the traditional T s - V I models. Its essence is to transform the T s - V I feature space from regional to pixel scale on the basis of surface energy balance principle. Consequently, the ET estimation and partitioning was only related to the boundary conditions at pixel scale, regardless of the T s - V I configuration over the spatial domain. We demonstrated the framework with MODIS (Moderate Resolution Imaging Spectroradiometer) products in Qaidam Basin, a poorly gauged basin with arid ecosystems in the Qinghai-Tibet Plateau in China. The scheme was performed pixel by pixel using as much of the remote sensing observations as possible, aiming at that it could be applied to other poorly gauged regions. The comparative analysis indicates that our ET estimates agreed well with three readily available ET products and those retrieved from water balance analysis. The advantages of our universal T s - V I model mainly lie in its high spatial resolution and daily continuity, which enables it to capture the spatial details and temporal variations more accurately. The results show that our annual average ET estimation from 2001 to 2020 was around 179.20 mm/year, which was very close to its annual average precipitation. The annual average soil evaporation (E) and plant transpiration (T) was 168.77 and 10.43 mm/year, accounting for 94 % and 6 % of the total ET, respectively. ET in Qaidam Basin decreased generally from southeast to northwest and from surrounding mountains to the interior with significant vertical zonality. Consequently, ET of different landscapes followed the order: woodland > shrubland > alpine vegetation > alpine meadow > bare rock > alpine grassland > salt crust > desert grassland > bare soil > gobi > sandy land. As an arid basin, the spatial distribution of ET in Qaidam Basin was mainly controlled by precipitation. However, with the further decrease of temperature in high mountains, ET started to be controlled by energy availability rather than water availability. Accordingly, the variations of our ET estimates with altitude increased first and then decreased, with a peak value of 287.67 mm observed at altitudes of 4600–4800 m. [ABSTRACT FROM AUTHOR]

High speed becomes an important development direction of flywheel energy storage system (FESS) for higher energy storage density. However, the high speed leads to a wide-range and rapid speed variation (tens of thousands of revolutions in seconds) and a limited frequency modulation index, both of which aggravate the current harmonics and deteriorate the robustness of the discharge control, and even lead to instability. To address this issue, this article proposes a robust and practical discharge control strategy for high-speed FESS with RLC filter, which realizes speed adaptation and harmonic suppression. In this scheme, the linear extended state observer and two-degree-of-freedom internal model control (TDOF-IMC) are applied to FESS in the framework of linear active disturbance rejection control (LADRC). Besides, considering that high-speed FESS usually require sensorless control due to magnetic bearings, a reduced-order Luenberger observer for the investigated FESS is proposed. The salient feature of this strategy is to introduce the TDOF-IMC containing FESS dynamic information into LADRC, so that the discharge control is both practical and robust. Experiments and simulations verify the effectiveness of the control strategy. [ABSTRACT FROM AUTHOR]

Hybrid distribution transformer (HDT) is realized by augmenting the traditional low-frequency transformer with a fractionally rated converter. This article improves the HDT topology by assembling the LCL-type converters and presents the grid currents and load voltages quasi-proportional-resonant (PR) control strategies for this improved HDT. The PR control schemes are developed based on the established stationary frame dynamic models of HDT, and the effects of the controller parameters and LCL-filter parameters variation on the HDT's control performance and harmonic suppression ability are analyzed by the Bode diagrams and step responses. The key feature of this article is that, by using the resonant controller and LCL-type filters, the complex coordinate transformation can be avoided and the high-frequency harmonics can be well suppressed in the HDT application. The simulation and experiment results verify the effectiveness of the improved HDT and the proposed control strategies. [ABSTRACT FROM AUTHOR]