Let p be a prime. For any finite p-group G, the deep transfers T H,G ' : H / H ' → G ' / G " from the maximal subgroups H of index (G:H) = p in G to the derived subgroup G ' are introduced as an ...Let p be a prime. For any finite p-group G, the deep transfers T H,G ' : H / H ' → G ' / G " from the maximal subgroups H of index (G:H) = p in G to the derived subgroup G ' are introduced as an innovative tool for identifying G uniquely by means of the family of kernels ùd(G) =(ker(T H,G ')) (G: H) = p. For all finite 3-groups G of coclass cc(G) = 1, the family ùd(G) is determined explicitly. The results are applied to the Galois groups G =Gal(F3 (∞)/ F) of the Hilbert 3-class towers of all real quadratic fields F = Q(√d) with fundamental discriminants d > 1, 3-class group Cl3(F) □ C3 × C3, and total 3-principalization in each of their four unramified cyclic cubic extensions E/F. A systematic statistical evaluation is given for the complete range 1 d 7, and a few exceptional cases are pointed out for 1 d 8.展开更多
As the hydrocarbon generation and storage mechanisms of high quality shales of Upper Ordovician Wufeng Formation– Lower Silurian Longmaxi Formation remain unclear, based on geological conditions and experimental mode...As the hydrocarbon generation and storage mechanisms of high quality shales of Upper Ordovician Wufeng Formation– Lower Silurian Longmaxi Formation remain unclear, based on geological conditions and experimental modelling of shale gas formation, the shale gas generation and accumulation mechanisms as well as their coupling relationships of deep-water shelf shales in Wufeng–Longmaxi Formation of Sichuan Basin were analyzed from petrology, mineralogy, and geochemistry. The high quality shales of Wufeng–Longmaxi Formation in Sichuan Basin are characterized by high thermal evolution, high hydrocarbon generation intensity, good material base, and good roof and floor conditions;the high quality deep-water shelf shale not only has high biogenic silicon content and organic carbon content, but also high porosity coupling. It is concluded that:(1) The shales had good preservation conditions and high retainment of crude oil in the early times, and the shale gas was mainly from cracking of crude oil.(2) The biogenic silicon(opal A) turned into crystal quartz in early times of burial diagenesis, lots of micro-size intergranular pores were produced in the same time;moreover, the biogenic silicon frame had high resistance to compaction, thus it provided the conditions not only for oil charge in the early stage, but also for formation and preservation of nanometer cellular-like pores, and was the key factor enabling the preservation of organic pores.(3) The high quality shale of Wufeng–Longmaxi Formation had high brittleness, strong homogeneity, siliceous intergranular micro-pores and nanometer organic pores, which were conducive to the formation of complicated fissure network connecting the siliceous intergranular nano-pores, and thus high and stable production of shale gas.展开更多
Present day power scenarios demand a high quality uninterrupted power supply and needs environmental issues to be addressed. Both concerns can be dealt with by the introduction of the renewable sources to the existing...Present day power scenarios demand a high quality uninterrupted power supply and needs environmental issues to be addressed. Both concerns can be dealt with by the introduction of the renewable sources to the existing power system. Thus, automatic generation control(AGC) with diverse renewable sources and a modified-cascaded controller are presented in the paper.Also, a new hybrid scheme of the improved teaching learning based optimization-differential evolution(hITLBO-DE) algorithm is applied for providing optimization of controller parameters. A study of the system with a technique such as TLBO applied to a proportional integral derivative(PID), integral double derivative(IDD) and PIDD is compared to hITLBO-DE tuned cascaded controller with dynamic load change.The suggested methodology has been extensively applied to a 2-area system with a diverse source power system with various operation time non-linearities such as dead-band of, generation rate constraint and reheat thermal units. The multi-area system with reheat thermal plants, hydel plants and a unit of a wind-diesel combination is tested with the cascaded controller scheme with a different controller setting for each area. The variation of the load is taken within 1% to 5% of the connected load and robustness analysis is shown by modifying essential factors simultaneously by± 30%. Finally, the proposed scheme of controller and optimization technique is also tested with a 5-equal area thermal system with non-linearities. The simulation results demonstrate the superiority of the proposed controller and algorithm under a dynamically changing load.展开更多
The kinetic parameters of hydrocarbon generation are determined through experimental simulation and mathematical calculation using four typical samples selected from the Cretaceous Nenjiang Formation in the northwest ...The kinetic parameters of hydrocarbon generation are determined through experimental simulation and mathematical calculation using four typical samples selected from the Cretaceous Nenjiang Formation in the northwest of Songliao Basin,Chang 7 Member of Triassic Yanchang Formation in the southwest of Ordos Basin,Paleogene in the southwest of Qaidam Basin,and Lucaogou Formation of Jimusar Sag in the east of Junggar Basin.The results show that activation energy of hydrocarbon generation of organic matter is closely related to maturity and mainly ranges between 197 kJ/mol and 227 kJ/mol.On this basis,the temperature required for organic matter in shale to convert into oil was calculated.The ideal heating temperature is between 270℃and 300℃,and the conversation rate can reach 90%after 50-300 days of heating at constant temperature.When the temperature rises at a constant rate,the temperature corresponding to the major hydrocarbon generation period ranges from 225 to 350℃at the temperature rise rate of 1-150℃/month.In order to obtain higher economic benefits,it is suggested to adopt higher temperature rise rate(60-150℃/month).The more reliable kinetic parameters obtained can provide a basis for designing more reasonable scheme of in-situ heating conversion.展开更多
The energy loss of the power grid is one of the key factors affecting the economic operation of power systems. How to calculate the electric energy consumption accurately will have a great influence on the planning, o...The energy loss of the power grid is one of the key factors affecting the economic operation of power systems. How to calculate the electric energy consumption accurately will have a great influence on the planning, operation and management of the power grid. Currently there is a mountain of theoretical methods to calculate the line loss of the power system. However, these methods have some limitation, such as less considering the volatility of wind power resources. This paper presents an improved method to calculate the energy loss of wind power generation, considering the fluctuations of wind power generation. First, data are collected to obtain the curve of the typical daily expected output of wind farms for one month. Second, the curve of the typical daily expected output are corrected by the average electricity and the shape factor to obtain the curve of the typical daily equivalent output of wind farms for one month. Finally, the power flow is calculated by using typical daily equivalent output curve to describe the energy loss for one month. The results in the 110 kV main network show that the method is feasible.展开更多
The rapid spreading of the Photovoltaic (PV) Systems as Distributed Generation (DG) in medium and low voltage networks created many effects and changes on the existing power system networks. In this work, two methods ...The rapid spreading of the Photovoltaic (PV) Systems as Distributed Generation (DG) in medium and low voltage networks created many effects and changes on the existing power system networks. In this work, two methods have been used and applied to determine the optimal allocation and sizing of the PV to be installed as DGs (ranging from 250 kW up to 3 MW). The first one is to determine the location according to the maximal power losses reduction over the feeder. The second one is by using the Harmony Search Algorithm which is claimed to be a powerful technique for optimal allocation of PV systems. The results of the two techniques were compared and found to be nearly closed. Furthermore, investigation on the effects on the feeder in terms of voltage levels, power factor readings, and short circuit current levels has been done. All calculations and simulations are conducted by using the MATLAB Simulation Program. Some field calculations and observations have been expended in order to substantiate the research findings and validation.展开更多
A big step forward to improve power system monitoring and performance, continued load growth without a corresponding increase in transmission resources has resulted in reduced operational margins for many power system...A big step forward to improve power system monitoring and performance, continued load growth without a corresponding increase in transmission resources has resulted in reduced operational margins for many power systems worldwide and has led to operation of power systems closer to their stability limits and to power exchange in new patterns. These issues, as well as the on-going worldwide trend towards deregulation of the entire industry on the one hand and the increased need for accurate and better network monitoring on the other hand, force power utilities exposed to this pressure to demand new solutions for wide area monitoring, protection and control. Wide-area monitoring, protection, and control require communicating the specific-node information to a remote station but all information should be time synchronized so that to neutralize the time difference between information. It gives a complete simultaneous snap shot of the power system. The conventional system is not able to satisfy the time-synchronized requirement of power system. Phasor Measurement Unit (PMU) is enabler of time-synchronized measurement, it communicate the synchronized local information to remote station.展开更多
The power systems economic and safety operation considering large-scale wind power penetration are now facing great challenges, which are based on reliable power supply and predictable load demands in the past. A roll...The power systems economic and safety operation considering large-scale wind power penetration are now facing great challenges, which are based on reliable power supply and predictable load demands in the past. A rolling generation dispatch model based on ultra-short-term wind power forecast was proposed. In generation dispatch process, the model rolling correct not only the conventional units power output but also the power from wind farm, simultaneously. Second order Markov chain model was utilized to modify wind power prediction error state (WPPES) and update forecast results of wind power over the remaining dispatch periods. The prime-dual affine scaling interior point method was used to solve the proposed model that taken into account the constraints of multi-periods power balance, unit output adjustment, up spinning reserve and down spinning reserve.展开更多
In the past decade or so,AI(artificial intelligence)technology has been growing with such a mesmerizing speed that today its presence in almost any industry that deals with any huge sheer volume of data is taking adva...In the past decade or so,AI(artificial intelligence)technology has been growing with such a mesmerizing speed that today its presence in almost any industry that deals with any huge sheer volume of data is taking advantage of AI by integrating it into their day-to-day operation.Meanwhile,seven billion people worldwide shape the world’s energy system and directly impact the fundamental drivers of energy,both renewable and non-renewable sources,to meet the demand for electricity from them.These energy sources can be reached from nature such as solar,wind,etc.,and human-made such as NPPs(nuclear power plants)in the form of either fission as an old technology since the Manhattan project and in the near future as fusion in the form of magnetic or inertial confinements.Meanwhile,AI controlling nuclear reactors are about to happen.The basic idea is to apply AI with its two subset components as ML(machine learning),and DL(deep learning)techniques to go through the mountains of data that come from a reactor,spot patterns in it,and calling them to the unit’s human attention operators is not invadable either.Designers of such nuclear reactors will combine simulation and real-world data,comparing scenarios from each to develop“confidence[in]what they can predict and what is the range of uncertainty of their prediction”.Adding that,in the end,the operator will make the final decisions in order to keep these power plants safe while they are in operation and how to secure them against cyber-attack natural or human-made disasters.In this short communication article,we would like to see how we can prove some of these concepts;then a NPP manufacturer can pick it up and use it in their designs of a new generation of these reactors.展开更多
The Hot Dry Rock(HDR)is considered as a clean and renewable energy,poised to significantly contribute to the global energy decarbonization agenda.Many HDR projects worldwide have accumulated valuable experience in eff...The Hot Dry Rock(HDR)is considered as a clean and renewable energy,poised to significantly contribute to the global energy decarbonization agenda.Many HDR projects worldwide have accumulated valuable experience in efficient drilling and completion,reservoir construction,and fracture simulation.In 2019,China Geological Survey(CGS)initiated a demonstration project of HDR exploration and production in the Gonghe Basin,aiming to overcome the setbacks faced by HDR projects.Over the ensuing four years,the Gonghe HDR project achieved the first power generation in 2021,followed by the second power generation test in 2022.After establishing the primary well group in the initial phase,two directional wells and one branch well were drilled.Noteworthy progress was made in successfully constructing the targeted reservoir,realizing inter-well connectivity,power generation and grid connection,implementing of the real-time micro-seismic monitoring.A closed-loop technical validation of the HDR exploration and production was completed.However,many technical challenges remain in the process of HDR industrialization,such as reservoir fracture network characterization,efficient drilling and completion,multiple fracturing treatment,continuous injection and production,as well as mitigation of induced seismicity and numerical simulation technology.展开更多
The world's population is growing,leading to an increasing demand for freshwater resources for drinking,sanitation,agriculture,and industry.Interfacial solar steam generation(ISSG)can solve many problems,such as m...The world's population is growing,leading to an increasing demand for freshwater resources for drinking,sanitation,agriculture,and industry.Interfacial solar steam generation(ISSG)can solve many problems,such as mitigating the power crisis,minimizing water pollution,and improving the purification and desalination of seawater,rivers/lakes,and wastewater.Cellulosic materials are a viable and ecologically sound technique for capturing solar energy that is adaptable to a range of applications.This review paper aims to provide an overview of current advancements in the field of cellulose-based materials ISSG devices,specifically focusing on their applications in water purification and desalination.This paper examines the cellulose-based materials ISSG system and evaluates the effectiveness of various cellulosic materials,such as cellulose nanofibers derived from different sources,carbonized wood materials,and two-dimensional(2D)and 3D cellulosic-based materials from various sources,as well as advanced cellulosic materials,including bacterial cellulose and cellulose membranes obtained from agricultural and industrial cellulose wastes.The focus is on exploring the potential applications of these materials in ISSG devices for water desalination,purification,and treatment.The function,advantages,and disadvantages of cellulosic materials in the performance of ISSG devices were also deliberated throughout our discussion.In addition,the potential and suggested methods for enhancing the utilization of cellulose-based materials in the field of ISSG systems for water desalination,purification,and treatment were also emphasized.展开更多
Based on a general theory of descendant trees of finite p-groups and the virtual periodicity isomorphisms between the branches of a coclass subtree, the behavior of algebraic invariants of the tree vertices and their ...Based on a general theory of descendant trees of finite p-groups and the virtual periodicity isomorphisms between the branches of a coclass subtree, the behavior of algebraic invariants of the tree vertices and their automorphism groups under these isomorphisms is described with simple transformation laws. For the tree of finite 3-groups with elementary bicyclic commutator qu-otient, the information content of each coclass subtree with metabelian main-line is shown to be finite. As a striking novelty in this paper, evidence is provided of co-periodicity isomorphisms between coclass forests which reduce the information content of the entire metabelian skeleton and a significant part of non-metabelian vertices to a finite amount of data.展开更多
A controllable strategy for eliciting nuclear fusion is presented through ultra-intenselaser derived positron generation by a conceptual first physics perspective. The capability to generate positrons on demand in a c...A controllable strategy for eliciting nuclear fusion is presented through ultra-intenselaser derived positron generation by a conceptual first physics perspective. The capability to generate positrons on demand in a controlled manner through an ultra-intense laser incident on a high atomic number target, such as gold, is the intrinsic core to the foundation of controllable nuclear fusion. Positron antimatter generated from the periphery of the fusion fuel pellet provides the basis for initiating the fusion reaction, which is regulated by controlling the operation of the ultra-intense laser. A dual pulsed Fast Ignition mechanism is selected to achieve the fusion reaction. Based on first physics performance analysis the controllable strategy for eliciting nuclear fusion through ultra-intenselaser derived positron generation offers a realizable means for achieving regulated nuclear fusion. A future perspective of the controllable fusion strategy addresses the opportunities and concerns of a pathway toward regulated nuclear fusion.展开更多
This study aims to develop an economic evaluation method for installing photovoltaic power generation in ordinary homes using GIS (Geographic Information Systems). The conclusions can be summarized in the following th...This study aims to develop an economic evaluation method for installing photovoltaic power generation in ordinary homes using GIS (Geographic Information Systems). The conclusions can be summarized in the following three points: 1) This method determines the profit and loss and payback period in order to evaluate the installation of photovoltaic power generation, taking into account the price of equipment, solar battery module conversion efficiency, subsidy, electricity purchase price, service life and rate for selling electricity. 2) The proposed evaluation method was applied to Kanagawa Prefecture in Japan, providing plural scenarios. Using a solar battery module conversion efficiency of more than 15%, it is possible to make the payback period shorter than the 20-year service life and anticipate a profit in almost the whole area. 3) The areas suitable for photovoltaic power generation are Kawasaki City and Ninomiya-machi. It is necessary to adopt measures to increase the subsidy and install photovoltaic power generating systems in specific places in areas where subsidies are not provided in enough amounts.展开更多
In this paper, a design method for ocean wave permanent magnet synchronous generator(PMSG)is proposed with new performance criteria to obtain better output performance at the cost of less permanent magnet material. Be...In this paper, a design method for ocean wave permanent magnet synchronous generator(PMSG)is proposed with new performance criteria to obtain better output performance at the cost of less permanent magnet material. Besides, a simple equivalent analytical geometry method is put forward to calculate the sizes of permanent magnets. Based on geometric and electromagnetic models, four types of rotor structures are compared, i.e., embedded, tangential, tile surface mount and convex surface mount structures. The designs and comparisons of machine are performed with the same permanent magnet volume. Moreover, the influences of mechanical pole-arc coefficient of tile surface mount PMSG on electrical efficiency, output power, material corrosion, core loss, and torque ripple are investigated. Finite-element analysis method is applied to verify the results using Ansoft/Maxwell.展开更多
Being photovoltaic power generation affected by radiation strength, wind speed, clouds cover and environment temperature, the generating in each moment is fluctuating. The operational characteristics of grid-connected...Being photovoltaic power generation affected by radiation strength, wind speed, clouds cover and environment temperature, the generating in each moment is fluctuating. The operational characteristics of grid-connected PV systems are coincided with gray theory application conditions. A gray theory model has been applied in short-term forecast of grid-connected photovoltaic system. The verification model of the probability of small error will help to check the accuracy of the gray forecast results. The calculated result shows that the ?model accuracy has been greatly enhanced.展开更多
BACKGROUND Hereditary spherocytosis(HS)is a hereditary disease of hemolytic anemia that occurs due to the erythrocyte membrane defects.Dubin–Johnson syndrome(DJS),which commonly results in jaundice,is a benign heredi...BACKGROUND Hereditary spherocytosis(HS)is a hereditary disease of hemolytic anemia that occurs due to the erythrocyte membrane defects.Dubin–Johnson syndrome(DJS),which commonly results in jaundice,is a benign hereditary disorder of bilirubin clearance that occurs only rarely.The co-occurrence of HS and DJS is extremely rare.We recently diagnosed and treated a case of co-occurring HS and DJS.CASE SUMMARY A 21-year-old female patient presented to our department because of severe jaundice,severe splenomegaly,and mild anemia since birth.We eventually confirmed the diagnosis of co-occurring DJS and HS by next generation sequencing(NGS).The treatment of ursodeoxycholic acid in combination with phenobarbital successfully increased hemoglobin and reduced total bilirubin and direct bilirubin.CONCLUSION The routine application of NGS can efficiently render a definite diagnosis when inherited disorders are suspected.展开更多
The Multi Year Tariff Order (MYTO) is the Nigerian Electricity Regulatory Commission (NERC) pricing framework for determining the Nigerian Electricity Supply Industry (NESI) pricing model. One of the objectives of the...The Multi Year Tariff Order (MYTO) is the Nigerian Electricity Regulatory Commission (NERC) pricing framework for determining the Nigerian Electricity Supply Industry (NESI) pricing model. One of the objectives of the NERC’s MYTO pricing model is to ensure regulated electricity end user tariff without compromising return on investment. Achieving this objective is imperative to attract investors in the growing Nigerian electricity market. However, NESI has hitherto been faced with challenges ranging from its inability to provide sufficient power to its customers to not being viable enough to provide return on capital invested. In this paper, sensitivity analysis of power plant operation and performance parameters on the cost of electricity (CoE) generation using MYTO (power generation) pricing model were evaluated. Thermodynamic modeling and simulation of an open cycle gas turbine (OCGT) was carried out to augment scarce data on power plant performance and operation in Nigeria. Sensitivity analysis was carried out using probabilistic method based on Monte Carlo simulation (MCS) implemented in commercial software (@ Risk®). The result highlighted sensitivity of the model input parameters to cost of electricity generation based on technical and financial assumptions of MYTO model. Seven most influential parameters affecting generation cost were identified. These parameters and their correlation coefficients are given as: 1) foreign exchange rate, 0.76;2) cost of fuel, 0.51;3) thermal efficiency, -0.23;4) variable operation and maintenance cost, 0.22;5) fixed operating and maintenance cost, -0.03;6) capacity factor, -0.02;and 7) average capacity degradation, 0.01. Based on the gas turbine engine and input parameter distributions statistics for this study, the generation cost lies between 9.84 to 15.45 N/kWh and the probabilities of CoE within these values were established.展开更多
Radiation effects on free convection MHD Couette flow started exponentially with variable wall temperature in the presence of heat generation have been studied. The governing equations are solved analytically using th...Radiation effects on free convection MHD Couette flow started exponentially with variable wall temperature in the presence of heat generation have been studied. The governing equations are solved analytically using the Laplace transform technique. The variations of velocity and fluid temperature are presented graphically. It is observed that the velocity decreases with an increase in either magnetic parameter or radiation parameter or Prandtl number. It is also observed that the velocity increases with an increase in either heat generation parameter or Grashof number or accelerated parameter or time. An increase in either radiation parameter or Prandtl number leads to fall in the fluid temperature. It is seen that the fluid temperature increases with an increase in either heat generation parameter or time. Further, it is seen that the shear stress at the moving plate decreases with an increase in either magnetic parameter or radiation parameter while it increases with an increase in either heat generation parameter or Prandtl number. The rate of heat transfer increases with an increase in either Prandtl number or time whereas it decreases with an increase in heat generation parameter.展开更多
Wireless Body Area Network (WBAN) is considered to apply to both medical healthcare and entertainment applications. A requirement for each application is different, i.e. high reliability for medical healthcare whereas...Wireless Body Area Network (WBAN) is considered to apply to both medical healthcare and entertainment applications. A requirement for each application is different, i.e. high reliability for medical healthcare whereas high throughput for entertainment application. However, for both applications, low energy consumption is requested. Multiple hops technics have been researching in many fields of wireless system, e.g., ad hod, mobile, ITS etc. and its energy-efficiency is reported to be high. We propose the multiple hops technic for WBAN, however, WBAN is different to another systems, almost sensors forward the vital data packet of another sensors while sensing and generating the data packet of itself. Therefore, according to a packet generation rate of all sensors, probabilities of successful transmission and packet loss because of collision, timeout and overflow, are changed. It means that the vital data is lost and the transmit power is wasted due to packet loss. In order to obtain the highest throughput and save the power, the successful transmission probability is analyzed and the packet generation rate is optimized for multiple hops WBAN that using CSMA/CA based on IEEE802.15.6. The numerical calculation result indicates that the optimized packet generation rate depends on the system model. Moreover, the relation between the system model, the optimized packet generation rate and the throughput is discussed in the paper.展开更多
文摘Let p be a prime. For any finite p-group G, the deep transfers T H,G ' : H / H ' → G ' / G " from the maximal subgroups H of index (G:H) = p in G to the derived subgroup G ' are introduced as an innovative tool for identifying G uniquely by means of the family of kernels ùd(G) =(ker(T H,G ')) (G: H) = p. For all finite 3-groups G of coclass cc(G) = 1, the family ùd(G) is determined explicitly. The results are applied to the Galois groups G =Gal(F3 (∞)/ F) of the Hilbert 3-class towers of all real quadratic fields F = Q(√d) with fundamental discriminants d > 1, 3-class group Cl3(F) □ C3 × C3, and total 3-principalization in each of their four unramified cyclic cubic extensions E/F. A systematic statistical evaluation is given for the complete range 1 d 7, and a few exceptional cases are pointed out for 1 d 8.
基金Supported by the China National Science and Technology Major Project(2017ZX05036,2017ZX05036001).
文摘As the hydrocarbon generation and storage mechanisms of high quality shales of Upper Ordovician Wufeng Formation– Lower Silurian Longmaxi Formation remain unclear, based on geological conditions and experimental modelling of shale gas formation, the shale gas generation and accumulation mechanisms as well as their coupling relationships of deep-water shelf shales in Wufeng–Longmaxi Formation of Sichuan Basin were analyzed from petrology, mineralogy, and geochemistry. The high quality shales of Wufeng–Longmaxi Formation in Sichuan Basin are characterized by high thermal evolution, high hydrocarbon generation intensity, good material base, and good roof and floor conditions;the high quality deep-water shelf shale not only has high biogenic silicon content and organic carbon content, but also high porosity coupling. It is concluded that:(1) The shales had good preservation conditions and high retainment of crude oil in the early times, and the shale gas was mainly from cracking of crude oil.(2) The biogenic silicon(opal A) turned into crystal quartz in early times of burial diagenesis, lots of micro-size intergranular pores were produced in the same time;moreover, the biogenic silicon frame had high resistance to compaction, thus it provided the conditions not only for oil charge in the early stage, but also for formation and preservation of nanometer cellular-like pores, and was the key factor enabling the preservation of organic pores.(3) The high quality shale of Wufeng–Longmaxi Formation had high brittleness, strong homogeneity, siliceous intergranular micro-pores and nanometer organic pores, which were conducive to the formation of complicated fissure network connecting the siliceous intergranular nano-pores, and thus high and stable production of shale gas.
文摘Present day power scenarios demand a high quality uninterrupted power supply and needs environmental issues to be addressed. Both concerns can be dealt with by the introduction of the renewable sources to the existing power system. Thus, automatic generation control(AGC) with diverse renewable sources and a modified-cascaded controller are presented in the paper.Also, a new hybrid scheme of the improved teaching learning based optimization-differential evolution(hITLBO-DE) algorithm is applied for providing optimization of controller parameters. A study of the system with a technique such as TLBO applied to a proportional integral derivative(PID), integral double derivative(IDD) and PIDD is compared to hITLBO-DE tuned cascaded controller with dynamic load change.The suggested methodology has been extensively applied to a 2-area system with a diverse source power system with various operation time non-linearities such as dead-band of, generation rate constraint and reheat thermal units. The multi-area system with reheat thermal plants, hydel plants and a unit of a wind-diesel combination is tested with the cascaded controller scheme with a different controller setting for each area. The variation of the load is taken within 1% to 5% of the connected load and robustness analysis is shown by modifying essential factors simultaneously by± 30%. Finally, the proposed scheme of controller and optimization technique is also tested with a 5-equal area thermal system with non-linearities. The simulation results demonstrate the superiority of the proposed controller and algorithm under a dynamically changing load.
基金Supported by the PetroChina Science and Technology Major Project(2016E-0101).
文摘The kinetic parameters of hydrocarbon generation are determined through experimental simulation and mathematical calculation using four typical samples selected from the Cretaceous Nenjiang Formation in the northwest of Songliao Basin,Chang 7 Member of Triassic Yanchang Formation in the southwest of Ordos Basin,Paleogene in the southwest of Qaidam Basin,and Lucaogou Formation of Jimusar Sag in the east of Junggar Basin.The results show that activation energy of hydrocarbon generation of organic matter is closely related to maturity and mainly ranges between 197 kJ/mol and 227 kJ/mol.On this basis,the temperature required for organic matter in shale to convert into oil was calculated.The ideal heating temperature is between 270℃and 300℃,and the conversation rate can reach 90%after 50-300 days of heating at constant temperature.When the temperature rises at a constant rate,the temperature corresponding to the major hydrocarbon generation period ranges from 225 to 350℃at the temperature rise rate of 1-150℃/month.In order to obtain higher economic benefits,it is suggested to adopt higher temperature rise rate(60-150℃/month).The more reliable kinetic parameters obtained can provide a basis for designing more reasonable scheme of in-situ heating conversion.
文摘The energy loss of the power grid is one of the key factors affecting the economic operation of power systems. How to calculate the electric energy consumption accurately will have a great influence on the planning, operation and management of the power grid. Currently there is a mountain of theoretical methods to calculate the line loss of the power system. However, these methods have some limitation, such as less considering the volatility of wind power resources. This paper presents an improved method to calculate the energy loss of wind power generation, considering the fluctuations of wind power generation. First, data are collected to obtain the curve of the typical daily expected output of wind farms for one month. Second, the curve of the typical daily expected output are corrected by the average electricity and the shape factor to obtain the curve of the typical daily equivalent output of wind farms for one month. Finally, the power flow is calculated by using typical daily equivalent output curve to describe the energy loss for one month. The results in the 110 kV main network show that the method is feasible.
文摘The rapid spreading of the Photovoltaic (PV) Systems as Distributed Generation (DG) in medium and low voltage networks created many effects and changes on the existing power system networks. In this work, two methods have been used and applied to determine the optimal allocation and sizing of the PV to be installed as DGs (ranging from 250 kW up to 3 MW). The first one is to determine the location according to the maximal power losses reduction over the feeder. The second one is by using the Harmony Search Algorithm which is claimed to be a powerful technique for optimal allocation of PV systems. The results of the two techniques were compared and found to be nearly closed. Furthermore, investigation on the effects on the feeder in terms of voltage levels, power factor readings, and short circuit current levels has been done. All calculations and simulations are conducted by using the MATLAB Simulation Program. Some field calculations and observations have been expended in order to substantiate the research findings and validation.
文摘A big step forward to improve power system monitoring and performance, continued load growth without a corresponding increase in transmission resources has resulted in reduced operational margins for many power systems worldwide and has led to operation of power systems closer to their stability limits and to power exchange in new patterns. These issues, as well as the on-going worldwide trend towards deregulation of the entire industry on the one hand and the increased need for accurate and better network monitoring on the other hand, force power utilities exposed to this pressure to demand new solutions for wide area monitoring, protection and control. Wide-area monitoring, protection, and control require communicating the specific-node information to a remote station but all information should be time synchronized so that to neutralize the time difference between information. It gives a complete simultaneous snap shot of the power system. The conventional system is not able to satisfy the time-synchronized requirement of power system. Phasor Measurement Unit (PMU) is enabler of time-synchronized measurement, it communicate the synchronized local information to remote station.
文摘The power systems economic and safety operation considering large-scale wind power penetration are now facing great challenges, which are based on reliable power supply and predictable load demands in the past. A rolling generation dispatch model based on ultra-short-term wind power forecast was proposed. In generation dispatch process, the model rolling correct not only the conventional units power output but also the power from wind farm, simultaneously. Second order Markov chain model was utilized to modify wind power prediction error state (WPPES) and update forecast results of wind power over the remaining dispatch periods. The prime-dual affine scaling interior point method was used to solve the proposed model that taken into account the constraints of multi-periods power balance, unit output adjustment, up spinning reserve and down spinning reserve.
文摘In the past decade or so,AI(artificial intelligence)technology has been growing with such a mesmerizing speed that today its presence in almost any industry that deals with any huge sheer volume of data is taking advantage of AI by integrating it into their day-to-day operation.Meanwhile,seven billion people worldwide shape the world’s energy system and directly impact the fundamental drivers of energy,both renewable and non-renewable sources,to meet the demand for electricity from them.These energy sources can be reached from nature such as solar,wind,etc.,and human-made such as NPPs(nuclear power plants)in the form of either fission as an old technology since the Manhattan project and in the near future as fusion in the form of magnetic or inertial confinements.Meanwhile,AI controlling nuclear reactors are about to happen.The basic idea is to apply AI with its two subset components as ML(machine learning),and DL(deep learning)techniques to go through the mountains of data that come from a reactor,spot patterns in it,and calling them to the unit’s human attention operators is not invadable either.Designers of such nuclear reactors will combine simulation and real-world data,comparing scenarios from each to develop“confidence[in]what they can predict and what is the range of uncertainty of their prediction”.Adding that,in the end,the operator will make the final decisions in order to keep these power plants safe while they are in operation and how to secure them against cyber-attack natural or human-made disasters.In this short communication article,we would like to see how we can prove some of these concepts;then a NPP manufacturer can pick it up and use it in their designs of a new generation of these reactors.
基金Funded by the“Investigation and Evaluation of the Hot Dry Rock Resources in the Guide-Dalianhai Area of the Gonghe Basin,Qinghai”(DD20211336,DD20211337,DD20211338)“Hot Dry Rock Resources Exploration and Production Demonstration Project”(DD20230018)of the China Geological Survey。
文摘The Hot Dry Rock(HDR)is considered as a clean and renewable energy,poised to significantly contribute to the global energy decarbonization agenda.Many HDR projects worldwide have accumulated valuable experience in efficient drilling and completion,reservoir construction,and fracture simulation.In 2019,China Geological Survey(CGS)initiated a demonstration project of HDR exploration and production in the Gonghe Basin,aiming to overcome the setbacks faced by HDR projects.Over the ensuing four years,the Gonghe HDR project achieved the first power generation in 2021,followed by the second power generation test in 2022.After establishing the primary well group in the initial phase,two directional wells and one branch well were drilled.Noteworthy progress was made in successfully constructing the targeted reservoir,realizing inter-well connectivity,power generation and grid connection,implementing of the real-time micro-seismic monitoring.A closed-loop technical validation of the HDR exploration and production was completed.However,many technical challenges remain in the process of HDR industrialization,such as reservoir fracture network characterization,efficient drilling and completion,multiple fracturing treatment,continuous injection and production,as well as mitigation of induced seismicity and numerical simulation technology.
基金This study was supported by Key Research and Development Program of Hubei Province(No.2022ACA002).
文摘The world's population is growing,leading to an increasing demand for freshwater resources for drinking,sanitation,agriculture,and industry.Interfacial solar steam generation(ISSG)can solve many problems,such as mitigating the power crisis,minimizing water pollution,and improving the purification and desalination of seawater,rivers/lakes,and wastewater.Cellulosic materials are a viable and ecologically sound technique for capturing solar energy that is adaptable to a range of applications.This review paper aims to provide an overview of current advancements in the field of cellulose-based materials ISSG devices,specifically focusing on their applications in water purification and desalination.This paper examines the cellulose-based materials ISSG system and evaluates the effectiveness of various cellulosic materials,such as cellulose nanofibers derived from different sources,carbonized wood materials,and two-dimensional(2D)and 3D cellulosic-based materials from various sources,as well as advanced cellulosic materials,including bacterial cellulose and cellulose membranes obtained from agricultural and industrial cellulose wastes.The focus is on exploring the potential applications of these materials in ISSG devices for water desalination,purification,and treatment.The function,advantages,and disadvantages of cellulosic materials in the performance of ISSG devices were also deliberated throughout our discussion.In addition,the potential and suggested methods for enhancing the utilization of cellulose-based materials in the field of ISSG systems for water desalination,purification,and treatment were also emphasized.
文摘Based on a general theory of descendant trees of finite p-groups and the virtual periodicity isomorphisms between the branches of a coclass subtree, the behavior of algebraic invariants of the tree vertices and their automorphism groups under these isomorphisms is described with simple transformation laws. For the tree of finite 3-groups with elementary bicyclic commutator qu-otient, the information content of each coclass subtree with metabelian main-line is shown to be finite. As a striking novelty in this paper, evidence is provided of co-periodicity isomorphisms between coclass forests which reduce the information content of the entire metabelian skeleton and a significant part of non-metabelian vertices to a finite amount of data.
文摘A controllable strategy for eliciting nuclear fusion is presented through ultra-intenselaser derived positron generation by a conceptual first physics perspective. The capability to generate positrons on demand in a controlled manner through an ultra-intense laser incident on a high atomic number target, such as gold, is the intrinsic core to the foundation of controllable nuclear fusion. Positron antimatter generated from the periphery of the fusion fuel pellet provides the basis for initiating the fusion reaction, which is regulated by controlling the operation of the ultra-intense laser. A dual pulsed Fast Ignition mechanism is selected to achieve the fusion reaction. Based on first physics performance analysis the controllable strategy for eliciting nuclear fusion through ultra-intenselaser derived positron generation offers a realizable means for achieving regulated nuclear fusion. A future perspective of the controllable fusion strategy addresses the opportunities and concerns of a pathway toward regulated nuclear fusion.
文摘This study aims to develop an economic evaluation method for installing photovoltaic power generation in ordinary homes using GIS (Geographic Information Systems). The conclusions can be summarized in the following three points: 1) This method determines the profit and loss and payback period in order to evaluate the installation of photovoltaic power generation, taking into account the price of equipment, solar battery module conversion efficiency, subsidy, electricity purchase price, service life and rate for selling electricity. 2) The proposed evaluation method was applied to Kanagawa Prefecture in Japan, providing plural scenarios. Using a solar battery module conversion efficiency of more than 15%, it is possible to make the payback period shorter than the 20-year service life and anticipate a profit in almost the whole area. 3) The areas suitable for photovoltaic power generation are Kawasaki City and Ninomiya-machi. It is necessary to adopt measures to increase the subsidy and install photovoltaic power generating systems in specific places in areas where subsidies are not provided in enough amounts.
基金Supported by the National Natural Science Foundation of China(No.51577124)Tianjin Research Program of Application Foundation and Advanced Technology(No.15JCZDJC32100)
文摘In this paper, a design method for ocean wave permanent magnet synchronous generator(PMSG)is proposed with new performance criteria to obtain better output performance at the cost of less permanent magnet material. Besides, a simple equivalent analytical geometry method is put forward to calculate the sizes of permanent magnets. Based on geometric and electromagnetic models, four types of rotor structures are compared, i.e., embedded, tangential, tile surface mount and convex surface mount structures. The designs and comparisons of machine are performed with the same permanent magnet volume. Moreover, the influences of mechanical pole-arc coefficient of tile surface mount PMSG on electrical efficiency, output power, material corrosion, core loss, and torque ripple are investigated. Finite-element analysis method is applied to verify the results using Ansoft/Maxwell.
文摘Being photovoltaic power generation affected by radiation strength, wind speed, clouds cover and environment temperature, the generating in each moment is fluctuating. The operational characteristics of grid-connected PV systems are coincided with gray theory application conditions. A gray theory model has been applied in short-term forecast of grid-connected photovoltaic system. The verification model of the probability of small error will help to check the accuracy of the gray forecast results. The calculated result shows that the ?model accuracy has been greatly enhanced.
基金Supported by the National Science and Technology Important and Special Project of China,No.2017ZX09304024
文摘BACKGROUND Hereditary spherocytosis(HS)is a hereditary disease of hemolytic anemia that occurs due to the erythrocyte membrane defects.Dubin–Johnson syndrome(DJS),which commonly results in jaundice,is a benign hereditary disorder of bilirubin clearance that occurs only rarely.The co-occurrence of HS and DJS is extremely rare.We recently diagnosed and treated a case of co-occurring HS and DJS.CASE SUMMARY A 21-year-old female patient presented to our department because of severe jaundice,severe splenomegaly,and mild anemia since birth.We eventually confirmed the diagnosis of co-occurring DJS and HS by next generation sequencing(NGS).The treatment of ursodeoxycholic acid in combination with phenobarbital successfully increased hemoglobin and reduced total bilirubin and direct bilirubin.CONCLUSION The routine application of NGS can efficiently render a definite diagnosis when inherited disorders are suspected.
文摘The Multi Year Tariff Order (MYTO) is the Nigerian Electricity Regulatory Commission (NERC) pricing framework for determining the Nigerian Electricity Supply Industry (NESI) pricing model. One of the objectives of the NERC’s MYTO pricing model is to ensure regulated electricity end user tariff without compromising return on investment. Achieving this objective is imperative to attract investors in the growing Nigerian electricity market. However, NESI has hitherto been faced with challenges ranging from its inability to provide sufficient power to its customers to not being viable enough to provide return on capital invested. In this paper, sensitivity analysis of power plant operation and performance parameters on the cost of electricity (CoE) generation using MYTO (power generation) pricing model were evaluated. Thermodynamic modeling and simulation of an open cycle gas turbine (OCGT) was carried out to augment scarce data on power plant performance and operation in Nigeria. Sensitivity analysis was carried out using probabilistic method based on Monte Carlo simulation (MCS) implemented in commercial software (@ Risk®). The result highlighted sensitivity of the model input parameters to cost of electricity generation based on technical and financial assumptions of MYTO model. Seven most influential parameters affecting generation cost were identified. These parameters and their correlation coefficients are given as: 1) foreign exchange rate, 0.76;2) cost of fuel, 0.51;3) thermal efficiency, -0.23;4) variable operation and maintenance cost, 0.22;5) fixed operating and maintenance cost, -0.03;6) capacity factor, -0.02;and 7) average capacity degradation, 0.01. Based on the gas turbine engine and input parameter distributions statistics for this study, the generation cost lies between 9.84 to 15.45 N/kWh and the probabilities of CoE within these values were established.
文摘Radiation effects on free convection MHD Couette flow started exponentially with variable wall temperature in the presence of heat generation have been studied. The governing equations are solved analytically using the Laplace transform technique. The variations of velocity and fluid temperature are presented graphically. It is observed that the velocity decreases with an increase in either magnetic parameter or radiation parameter or Prandtl number. It is also observed that the velocity increases with an increase in either heat generation parameter or Grashof number or accelerated parameter or time. An increase in either radiation parameter or Prandtl number leads to fall in the fluid temperature. It is seen that the fluid temperature increases with an increase in either heat generation parameter or time. Further, it is seen that the shear stress at the moving plate decreases with an increase in either magnetic parameter or radiation parameter while it increases with an increase in either heat generation parameter or Prandtl number. The rate of heat transfer increases with an increase in either Prandtl number or time whereas it decreases with an increase in heat generation parameter.
文摘Wireless Body Area Network (WBAN) is considered to apply to both medical healthcare and entertainment applications. A requirement for each application is different, i.e. high reliability for medical healthcare whereas high throughput for entertainment application. However, for both applications, low energy consumption is requested. Multiple hops technics have been researching in many fields of wireless system, e.g., ad hod, mobile, ITS etc. and its energy-efficiency is reported to be high. We propose the multiple hops technic for WBAN, however, WBAN is different to another systems, almost sensors forward the vital data packet of another sensors while sensing and generating the data packet of itself. Therefore, according to a packet generation rate of all sensors, probabilities of successful transmission and packet loss because of collision, timeout and overflow, are changed. It means that the vital data is lost and the transmit power is wasted due to packet loss. In order to obtain the highest throughput and save the power, the successful transmission probability is analyzed and the packet generation rate is optimized for multiple hops WBAN that using CSMA/CA based on IEEE802.15.6. The numerical calculation result indicates that the optimized packet generation rate depends on the system model. Moreover, the relation between the system model, the optimized packet generation rate and the throughput is discussed in the paper.