考虑风电反调峰特性的储能调峰优化策略

为解决风力发电并网的不确定性导致的电力系统调峰困难问题,提高新能源综合利用率,在深入分析储能调峰原理的基础上提出一种考虑风电调峰特性的储能调峰优化策略.首先介绍风电反调峰特性影响,根据调峰特性确定最低移峰功率和最高填谷功率,接着再综合考虑系统功率平衡约束、储能系统约束和电源测约束的基础上增加调峰可靠性约束,建立以负荷方差最小为目标的系统优化模型,最后构建计及调峰可靠性的评价指标.以某电网阶段时间内负荷数据为基础进行算例分析,对比恒功率策略,仿真结果验证本文方法调峰效果更优.     

裂缝稠油油藏流体流动裂缝开度界限初步探索

裂缝稠油油藏中,裂缝储量易开发,基质储量难开发。然而,划分裂缝和基质的开度界限及基质中微裂缝可流动开度下限均难以确定。针对A裂缝稠油油藏,基于渗流理论和微观机理实验,初步探索得到原油"可动"开度绝对下限3μm左右、原油"可动"开度技术下限10μm左右、原油"易动"开度绝对下限5μm左右、原油"易动"开度技术下限15μm左右、水驱油"最佳"开度界限40~50μm等5个A裂缝稠油油藏开度界限。可动开度下限可指导计算有效储量,易动开度下限可指导划分裂缝基质储量,水驱最佳开度界限可指导井位部署。研究思路与方法,对同类油藏开发研究具备一定借鉴意义。     

美国极轨气象卫星的转型探索

气象卫星是重要的国家基础性、战略性空间系统.美国极轨气象卫星体系通过融合美国国防部、美国海洋和大气管理局及欧洲气象卫星组织各自的极轨气象卫星系统,实现了全球全天时的持续覆盖能力.为获取高时效性全球范围气象卫星资料,近年来美国一直在探索气象卫星的转型发展.在梳理美国极轨气象卫星发展历程的基础上,分析了其多种转型探索,包括对美国国家海洋和大气管理局开展的新一代卫星架构研究项目,试点采购商业气象卫星数据,开展气象小卫星关键技术及载荷研究等.     

An Improved Underwater Confrontation Simulation Method of Naval Amphibious Operational Training System

This paper described an improved underwater confrontation simulation method of naval amphibious operational training system. The initial position of submarine forces on the enemy is generated automatically, and the attacking distance model of torpedoes is established based on the kinematics theory, which is more flexible and reasonable to judge the launch condition compared to traditional method. The two kinds of confrontation behavior models on the enemy submarine are created to depict its tactical action from the defensive to the offensive as well as the contrary, ensuring that operational style is simulated more comprehensively and properly. The existing motion trajectory estimation and collision detection algorithms on operational platforms are also improved to reduce the iteration error and further enhance the detection accuracy of target hit.     

A Simulation Method for Analyzing and Evaluating Rail System Performance Based on Speed Profile

This paper presents and discusses a simulation method for analyzing and evaluating system performance on a rail line from the perspective of speed profile. Dynamic analysis for train motions is introduced, and a discrete time-operation graph is proposed to represent the relation between speed profile and energy consumption. Based on them, an analytical model is formulated to provide a quick insight into the system performance. The discrete-time simulation (DTS) method is then implemented to study the system in detail. Compared to the existing simulations, two innovations are included in the DTS: (1) the analytical lookup tables that can simplify the dynamic computation and, (2) the speed profile adjustment process that forecasts and avoids future conflicts based on practical constraints. The numerical results show that the DTS speed profile has advantages over existing methods. Finally, the DTS method is used to analyze and evaluate the system performance of the current timetable on Beijing Yizhuang Metro Line. The results suggest that the current timetable is not robust enough, and thus possible improvements are discussed at both scheduling and operating stages. The proposed method is verified to be effective and reliable for practical uses.     

Connexins and pannexins in the skeleton: gap junctions,hemichannels and more

Regulation of bone homeostasis depends on the concerted actions of bone-forming osteoblasts and bone-resorbing osteoclasts, controlled by osteocytes, cells derived from osteoblasts surrounded by bone matrix. The control of differentiation, viability and function of bone cells relies on the presence of connexins. Connexin43 regulates the expression of genes required for osteoblast and osteoclast differentiation directly or by changing the levels of osteocytic genes, and connexin45 may oppose connexin43 actions in osteoblastic cells. Connexin37 is required for osteoclast differentiation and its deletion results in increased bone mass. Less is known on the role of connexins in cartilage, ligaments and tendons. Connexin43, connexin45, connexin32, connexin46 and connexin29 are expressed in chondrocytes, while connexin43 and connexin32 are expressed in ligaments and tendons. Similarly, although the expression of pannexin1, pannexin2 and pannexin3 has been demonstrated in bone and cartilage cells, their function in these tissues is not fully understood.     

Chaos and Nonlinear Feedback Control of the Arch Micro-Electro-Mechanical System

This paper addresses a nonlinear feedback control problem for the chaotic arch microelectro- mechanical system with unknown parameters, immeasurable states and partial state-constraint subjected to the distributed electrostatic actuation. To reflect inherent properties and design controller, the phase diagrams, bifurcation diagram and Poincare section are presented to investigate the nonlinear dynamics. The authors employ a symmetric barrier Lyapunov function to prevent violation of constraint when the arch micro-electro-mechanical system faces some limits. An RBF neural network system integrating with an update law is adopted to estimate unknown function with arbitrarily small error. To eliminate chaotic oscillation, a neuro-adaptive backstepping control scheme fused with an extended state tracking differentiator and an observer is constructed to lower requirements on measured states and precise system model. Besides, introducing an extended state tracking differentiator avoids repeated derivative for the virtual control signal associated with conventional backstepping. Finally, simulation results are presented to illustrate feasibility of the proposed scheme.     

Intrinsically disordered proteins in crowded milieu: when chaos prevails within the cellular gumbo

Effects of macromolecular crowding on structural and functional properties of ordered proteins, their folding, interactability, and aggregation are well documented. Much less is known about how macromolecular crowding might affect structural and functional behaviour of intrinsically disordered proteins (IDPs) or intrinsically disordered protein regions (IDPRs). To fill this gap, this review represents a systematic analysis of the available literature data on the behaviour of IDPs/IDPRs in crowded environment. Although it was hypothesized that, due to the excluded-volume effects present in crowded environments, IDPs/IDPRs would invariantly fold in the presence of high concentrations of crowding agents or in the crowded cellular environment, accumulated data indicate that, based on their response to the presence of crowders, IDPs/IDPRs can be grouped into three major categories, foldable, non-foldable, and unfoldable. This is because natural cellular environment is not simply characterized by the presence of high concentration of “inert” macromolecules, but represents an active milieu, components of which are engaged in direct physical interactions and soft interactions with target proteins. Some of these interactions with cellular components can cause (local) unfolding of query proteins. In other words, since crowding can cause both folding and unfolding of an IDP or its regions, the outputs of the placing of a query protein to the crowded environment would depend on the balance between these two processes. As a result, and because of the spatio-temporal heterogeneity in structural organization of IDPs, macromolecular crowding can differently affect structures of different IDPs. Recent studies indicate that some IDPs are able to undergo liquid–liquid-phase transitions leading to the formation of various proteinaceous membrane-less organelles (PMLOs). Although interiors of such PMLOs are self-crowded, being characterized by locally increased concentrations of phase-separating IDPs, these IDPs are minimally foldable or even non-foldable at all (at least within the physiologically safe time-frame of normal PMLO existence).     

Platelet-derived growth factor receptor beta identifies mesenchymal stem cells with enhanced engraftment to tissue injury and pro-angiogenic property

Mesenchymal stem cells (MSCs) are heterogeneous likely consisting of subpopulations with various therapeutic potentials. Here we attempted to acquire a subset of MSCs with enhanced effect in wound healing. We found that human placental MSCs expressing platelet-derived growth factor (PDGF) receptor (PDGFR)-β exhibited greater proliferation rates and generated more colony-forming unit-fibroblast (CFU-F), compared to PDGFR-β^? MSCs. Notably, PDGFR-β⁺ MSCs expressed higher levels of pro-angiogenic factors such as Ang1, Ang2, VEGF, bFGF and PDGF. When 10⁶ GFP-expressing MSCs were topically applied into excisional wounds in mice, PDGFR-β⁺ MSCs actively incorporated into the wound tissue, resulting in enhanced engraftment (3.92 ± 0.31 × 10⁵ remained in wound by 7 days) and accelerated wound closure; meanwhile, PDGFR-β^? MSCs tended to remain on the top of the wound bed with significantly fewer cells (2.46 ± 0.26 × 10⁵) engrafted into the wound, suggesting enhanced chemotactic migration and engraftment of PDGFR-β⁺ MSCs into the wound. Real-Time PCR and immunostain analyses revealed that the expression of PDGF-B was upregulated after wounding; transwell migration assay showed that PDGFR-β⁺ MSCs migrated eightfold more than PDGFR-β^? MSCs toward PDGF-BB. Intriguingly, PDGFR-β⁺ MSC-treated wounds showed significantly enhanced angiogenesis compared to PDGFR-β^? MSC- or vehicle-treated wounds. Thus, our results indicate that PDGFR-β identifies a subset of MSCs with enhanced chemotactic migration to wound injury and effect in promoting angiogenesis and wound healing, implying a greater therapeutic potential for certain diseases.