A Novel Soft Start Method of Super Large Capacity High Voltage Motor

The large current generated by starting directly of super large capacity and high voltage induction motor would have a huge impact on the grid as well as the motor itself.The variation of the power factor and electromagnetic torque during direct start of motors with different capacity and voltage levels are obtained.Aiming at the problem that the secondary impact of auto-transformer starter is too large and the cost of magnetic control starter is too high,the auto-transformer and magnetic control soft start method of super large capacity and high voltage motor is proposed and the basic working principle is analyzed.The calculation formula of cost for magnetic control soft starter and auto-transformer and magnetic control soft starter is deduced,and specific examples are analyzed and compared.It is concluded that the choice of auto-transformer with appropriate tapping ratio can greatly reduce the cost of auto-transformer and magnetic control soft starter compared with the other one.Finally,the simulation and experiment results show that the start method can effectively avoid secondary current impact and constrain the motor starting current to less than 2.5 times the rated current.

A Review of Reservoir Sedimentation Control and Storage Capacity Recovery

There are many reservoirs in China,and serious reservoir sedimentation affects reservoir function and reservoir safety.It is of great significance for restoring the reservoir capacity,improving the efficiency of the reservoir and prolonging the service life of the reservoir to carry out the research on reservoir sedimentation control and storage capacity recovery technology,in the case of fewer and fewer good dam sites suitable for the construction of the reservoir and the increasing accumulation of reservoir sedimentation.In this paper,influence factor of the storage loss,sedimentation control and reservoir capacity recovery technology in China are briefly reviewed.It is necessary to carry out research work on reservoir sedimentation investigation and reservoir siltation mechanism and control measures.

Recovery Capacity of the Finance System of Italian Municipalities After the Currency Crisis of 1992

This paper is a first pioneering attempt to apply the concept of resilience to the analysis of the public finance systems of local governments, a concept already used and ＂abused＂ in various disciplines and fields of science. In particular, it proposes an attempt to estimate the recovery capacity of Italian Municipalities in a crucial period of our country＇s financial history, between 1992 and 2000, or between the currency crisis and the introduction of the Euro. However, the analysis also involved the subsequent trends, in order to demonstrate that the current vulnerability of the municipal public finance system, in particular of the Municipalities of Southern Italy, depends not only on the economic cycle but also on the continuous and incessant changes in the financing mechanisms of local governments established by the central government. The analysis showed a lower financial resilience of the Municipalities of the Mezzogiorno （island and continental） compared to those of the Center-North. The determinants of this phenomenon were found, for one part, through the analysis of the financial data of the Italian Municipalities - as presented by the SVIMEZ in its annual reports on the economy of the Mezzogiomo - and, for another part, through the critical synthesis of significant economic events which occurred during the period examined.

Characteristics and mechanisms of supercritical CO_(2) flooding under different factors in low-permeability reservoirs

In recent years,supercritical CO_(2)flooding has become an effective method for developing lowpermeability reservoirs.In supercritical CO_(2)flooding different factors influence the mechanism of its displacement process for oil recovery.Asynchronous injection-production modes can use supercritical CO_(2)to enhance oil recovery but may also worsen the injection capacity.Cores with high permeability have higher oil recovery rates and better injection capacity,however,gas channeling occurs.Supercritical CO_(2)flooding has a higher oil recovery at high pressure levels,which delays the occurrence of gas channeling.Conversely,gas injection has lower displacement efficiency but better injection capacity at the high water cut stage.This study analyzes the displacement characteristics of supercritical CO_(2)flooding with a series of experiments under different injection and production parameters.Experimental results show that the gas breakthrough stage has the fastest oil production and the supercritical CO_(2)injection capacity variation tendency is closely related to the gas-oil ratio.Further experiments show that higher injection rates represent significant ultimate oil recovery and injection index,providing a good reference for developing low-permeability reservoirs.

Off-Design Simulation of a CSP Power Plant Integrated with aWaste Heat Recovery System

Concentrating Solar Power(CSP)plants offer a promising way to generate low-emission energy.However,these plants face challenges such as reduced sunlight during winter and cloudy days,despite being located in high solar radiation areas.Furthermore,their dispatch capacities and yields can be affected by high electricity consumption,particularly at night.The present work aims to develop an off-design model that evaluates the hourly and annual performances of a parabolic trough power plant(PTPP)equipped with a waste heat recovery system.The study aims to compare the performances of this new layout with those of the conventional Andasol 1 plant,with the aim of assessing the improvements achieved in the new design.Based on the results,it can be concluded that the new layout has increased the annual generated power to almost 183 GWh(an increase of about 7.60% is achieved compared to the Andasol 1 layout that generates 169 GWh annually).Additionally,the proposed installation has achieved an efficiency of 20.55%,which represents a 7.87% increase compared to the previous design(19.05%).The Levelized Cost of Electricity(LCOE)of the new layout has been reduced by more than 5.8% compared to the Andasol 1 plant.Specifically,it has decreased from 13.11 to 12.35 c/kWh.This reduction in LCOE highlights the improved cost-effectiveness of the newlayout,making it amore economically viable option for generating electricity compared to the conventional Andasol 1 plant.

Java中常用关键字使用与capacity方法应用浅析

近年来,随着社会对Java开发人才的需求日益迫切,广大开发人员学习Java语言的兴趣也与俱增。但是学习过程中遇到一些不太好解决的问题。本人根据自己数年学习和教学的经验,本文中浅析Java中几个重要的而又容易混淆的关键字和方法。对这一类问题进行简单明了地阐述,使得帮助读者能够从通俗易懂的例子和描述中掌握关键字this和super的使用及其capacity方法的应用。

The Voltage Distribution Characteristics of a Hybrid Circuit Breaker During High Current Interruption

Hybrid circuit breaker （HCB） technology based on a vacuum interrupter and a SF6 interrupter in series has become a new research direction because of the low-carbon requirements for high voltage switches. The vacuum interrupter has an excellent ability to deal with the steep rising part of the transient recovery voltage （TRV）, while the SF6 interrupter can withstand the peak part of the voltage easily. An HCB can take advantage of the interrupters in the current interruption process. In this study, an HCB model based on the vacuum ion diffusion equations, ion density equation, and modified Cassie-Mayr arc equation is explored. A simulation platform is constructed by using a set of software called the alternative transient program （ATP）. An HCB prototype is also designed, and the short circuit current is interrupted by the HCB under different action sequences of contacts. The voltage distribution of the HCB is analyzed through simulations and tests. The results demonstrate that if the vacuum interrupter withstands the initial TRV and interrupts the post-arc current first, then the recovery speed of the dielectric strength of the SF6 interrupter will be fast. The voltage distribution between two interrupters is determined by their post-arc resistance, which happens after current-zero, and subsequently, it is determined by the capacitive impedance after the post-arc current decays to zero.

Efficacy of chitosan and sodium alginate scaffolds for repair of spinal cord injury in rats

Spinal cord injury results in the loss of motor and sensory pathways and spontaneous regeneration of adult mammalian spinal cord neurons is limited. Chitosan and sodium alginate have good biocompatibility, biodegradability, and are suitable to assist the recovery of damaged tissues, such as skin, bone and nerve. Chitosan scaffolds, sodium alginate scaffolds and chitosan-sodium alginate scaffolds were separately transplanted into rats with spinal cord hemisection. Basso-Beattie-Bresnahan locomotor rating scale scores and electrophysiological results showed that chitosan scaffolds promoted recovery of locomotor capacity and nerve transduction of the experimental rats.Sixty days after surgery, chitosan scaffolds retained the original shape of the spinal cord. Compared with sodium alginate scaffolds- and chitosan-sodium alginate scaffolds-transplanted rats, more neurofilament-H-immunoreactive cells （regenerating nerve fibers） and less glial fibrillary acidic protein-immunoreactive cells （astrocytic scar tissue） were observed at the injury site of experimental rats in chitosan scaffold-transplanted rats. Due to the fast degradation rate of sodium alginate, sodium alginate scaffolds and composite material scaffolds did not have a supporting and bridging effect on the damaged tissue. Above all, compared with sodium alginate and composite material scaffolds, chitosan had better biocompatibility, could promote the regeneration of nerve fibers and prevent the formation of scar tissue,and as such, is more suitable to help the repair of spinal cord injury.

Progesterone modulates m TOR in the hippocampus of mice after traumatic brain injury

Spinal cord injury results in the loss of motor and sensory pathways and spontaneous regeneration of adult mammalian spinal cord neurons is limited. Chitosan and sodium alginate have good biocompatibility, biodegradability, and are suitable to assist the recovery of damaged tissues, such as skin, bone and nerve. Chitosan scaffolds, sodium alginate scaffolds and chitosan-sodium alginate scaffolds were separately transplanted into rats with spinal cord hemisection. Basso-Beattie-Bresnahan locomotor rating scale scores and electrophysiological results showed that chitosan scaffolds promoted recovery of locomotor capacity and nerve transduction of the experimental rats.Sixty days after surgery, chitosan scaffolds retained the original shape of the spinal cord. Compared with sodium alginate scaffolds- and chitosan-sodium alginate scaffolds-transplanted rats, more neurofilament-H-immunoreactive cells （regenerating nerve fibers） and less glial fibrillary acidic protein-immunoreactive cells （astrocytic scar tissue） were observed at the injury site of experimental rats in chitosan scaffold-transplanted rats. Due to the fast degradation rate of sodium alginate, sodium alginate scaffolds and composite material scaffolds did not have a supporting and bridging effect on the damaged tissue. Above all, compared with sodium alginate and composite material scaffolds, chitosan had better biocompatibility, could promote the regeneration of nerve fibers and prevent the formation of scar tissue,and as such, is more suitable to help the repair of spinal cord injury.

Generalized Physical Layer Channel Model for RelayBased Super Dense Networks

The κ-μ fading model is an advanced channel model in super dense wireless networks.In this paper,we evaluate the performance of the system over κ-μ fading channel in super dense relay networks with consideration of multiple independent but not necessarily identically distributed(i.n.i.d.) cochannel interference(CCI) under interferencelimited environment.More specifically,we derive a useful and accurate cumulative distribution function(CDF) expression of the end-to-end signal-to-interference plus noise(SINR) ratio.Moreover,we derive novel analytical expressions of the outage probability(OP),average bit error probability(ABEP) and average capacity for binary modulation types and arbitrary positive values of κ-and μ of such system.Furthermore,we propose asymptotic analysis for both the OP and ABEP to give physical insights.A simplified analytical form for the ABEP at high-SNR regimes is provided as well.Finally,the accuracy of the derived expressions is well validated by Monte Carlo simulations.

Epidural oscillating field stimulation increases axonal regenerative capacity and myelination after spinal cord trauma

Oscillating field stimulation(OFS)with regular alterations in the polarity of electric current is a unique,experimental approach to stimulate,support,and potentially guide the outgrowth of both sensory and motor nerve fibers after spinal cord injury(SCI).In previous experiments,we demonstrated the beneficial effects of OFS in a 4-week survival period after SCI.In this study,we observed the major behavioral,morphological,and protein changes in rats after 15 minutes of T9 spinal compression with a 40 g force,followed by long-lasting OFS(50μA),over a 8-week survival period.Three groups of rats were analyzed:rats after T9 spinal compression(SCI group);SCI rats subjected to implantation of active oscillating field stimulator(OFS+SCI group);and SCI rats subjected to nonfunctional OFS(nOFS+SCI group).Histopathological analysis of spinal tissue indicated a strong impact of epidural OFS on the reduction of tissue and myelin loss after SCI in the segments adjacent to the lesion site.Quantitative fluorescent analysis of the most affected areas of spinal cord tissue revealed a higher number of spared axons and oligodendrocytes of rats in the OFS+SCI group,compared with rats in the SCI and nOFS+SCI groups.The protein levels of neurofilaments(NF-l),growth-associated protein-43(marker for newly sprouted axons),and myelin basic protein in rats were signifiantly increased in the OFS+SCI group than in the nOFS+SCI and SCI groups.This suggests a supporting role of the OFS in axonal and myelin regeneration after SCI.Moreover,rats in the OFS+SCI group showed great improvements in sensory and motor functions than did rats in the nOFS+SCI and SCI groups.All these findings suggest that long-lasting OFS applied immediately after SCI can provide a good microenviroment for recovery of damaged spinal tissue by triggering regenreative processes in the acute phase of injury.

DOA estimation method for wideband signals by sparse recovery in frequency domain

The traditional super-resolution direction finding methods based on sparse recovery need to divide the estimation space into several discrete angle grids, which will bring the final result some error. To this problem, a novel method for wideband signals by sparse recovery in the frequency domain is proposed. The optimization functions are found and solved by the received data at every frequency, on this basis, the sparse support set is obtained, then the direction of arrival (DOA) is acquired by integrating the information of all frequency bins, and the initial signal can also be recovered. This method avoids the error caused by sparse recovery methods based on grid division, and the degree of freedom is also expanded by array transformation, especially it has a preferable performance under the circumstances of a small number of snapshots and a low signal to noise ratio (SNR).

Early Opportunity of CO_2 Storage in Coal Bed of China

A study to identify potential early opportunities for CO2 storage in coal bed has been performed. CO2-ECBM can enhances the recovery of coalbed methane,and also store CO2 in coal for geological time.CO2-ECBM is an effective measure for CO2 mitigation,and also enhance the recovery of coalbed methane that can reduce the cost of CO2 geological storage.The evaluation index system of feasibility

引进KROFTA超效气浮器处理纸机白水

吉林造纸（集团）有限公司是国内第一家引进瑞士 ＫＲＯＦＴＡ超效气浮器的企业，本文介绍了该超效气 浮器的构造、特点、工作原理及生产运行情况。

Application of Polymers in Low Permeability Formations

For low-permeability sandstone reservoir with big channel, we researched the novel deep profile method alternative injection of anionic and cationic polymer. Evaluating various factors on adsorption capacity through lab test, the results show that with the increase of temperature, the adsorption capacity decreases and the cationic polymer is easier to be absorbed. With the increase of salinity, adsorption time or polymer concentration, the adsorption capacity increases. The adsorption equilibrium concentration of cationic polymer is 1500 mg/L;adsorption equilibrium time is 8 h. The adsorption equilibrium concentration of anionic polymer is 1000 mg/L;adsorption equilibrium time is 6 h. Physical simulation experiment shows that alternative injection of anionic and cationic polymer is better than injection of single polymer, and preferential injection of cationic polymer is better than preferential injection of anionic polymer. With the increase of injection rounds, sealing capacity gets better, but in view of cost, the rounds should not be more than 3. The profile control technique can obviously enhanced oil recovery, and water displacement recovery increases 41%. 2 wells were tested successfully in Henan Oilfield in June 2010. Approximate 154.47 tons of incremental oil was obtained with 2% water-cut decrease.

The Application of Bamboo Network Reinforcement Technology on Hydraulic Fill Soft-Soil Foundation Treatment

To make a large area of dredger fill silt surface layer form working face and subsequent construction problems, the project conducts the bamboo network reinforcement in the silt surface layer. It makes the surface layer bearing capacity to meet the construction requirement of deep processing. Based on Shantou Municipal Road Embankment Treatment Engineering and the project, the bamboo network reinforcement technology to reinforce the dredger fill super soft soil surface layer is used. The results show that the bearing capacity of hydraulic fill super soft soil surface layer is 32.6 kPa after 3 months treatment. The surface layer bearing capacity after 3 months treatment improved 323% than the early treatment and increased 695% than no processing. The results indicate that the reinforcement effect is outstanding and provide the basis for drafting the dredger fill super soft soil surface layer treatment plan.

基于超级小区的SuperMIMO功能的应用研究

超级小区的SuperMIMO功能主要是结合超级小区+多天线MU-MIMO技术,该成果是一种创新性的无线通信解决方案,结合了超级小区和多天线多用户MU-MIMO技术的优点,在提升网络容量的同时解决干扰问题。超级小区将多个物理小区整合为一个大的虚拟小区,以扩展信号覆盖范围,可以改善小区边缘覆盖和减少干扰,提升用户的连接质量。MU-MIMO技术允许基站同时为多个用户设备提供服务,通过在同一时间片内传输多个数据流,提供多用户多输入多输出的可靠连接,MU-MIMO提高了频谱效率,而不会相互干扰,可以大幅提高网络的质量和效率。

浅谈中国未来大型水电装备技术挑战与创新

我国水电资源丰富、开发程度处于中等水平,远不及欧洲发达国家。“双碳”战略下,水电作为清洁能源,以其高调节性、高稳定性将在以新能源为主的新型电力系统中发挥“压舱石”作用。资源特点和经济性决定未来水电开发将朝向更高水头(高转速)、更大容量趋势发展,机组将具备高海拔环境运行、超高水头、超大容量的特点。开发难度极高,技术挑战前所未有,亟待攻克。该文从多个角度分析阐述特殊工况下我国水电装备开发面临的问题和技术挑战,探讨关键技术发展趋势以及创新技术应用潜力,为未来水电装备的技术创新和突破提供参考方向。