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The gas-fired generation has recently become an important power source for power systems. The increasing integration of gas-fired units (GFUs) brings a problem of location allocation strategy for power system planners. This paper proposes a bi-level maximum-minimum optimal placement model of GFUs to improve the static voltage stability in the transmission network. In the first stage, the locations of installed GFUs are optimized to improve the static voltage stability margin. The optimal installed capacity of GFUs is determined to minimize the operation costs and power losses in the second stage. The proposed mixed-integer nonlinear programming (MINLP) model is solved by second-order cone programming relaxations. Numerical results in the IEEE 118-bus test system demonstrate the effectiveness of the proposed method and the static voltage stability can be improved.

A novel fault isolation scheme in a power system based on wide-area information is proposed. Based on graph theory, the adjacency matrices for electrical components and circuit breakers are set up. To achieve this new scheme of fault isolation on a complex network, the wide-area switch status information is used. The real-time fault isolation set for each protected electrical component is obtained according to the changeable power network structures. The effectiveness of the proposed scheme is tested on a power system with the typical main electrical connection under a single fault, multiple faults, circuit breaker failure, and substation with the outage of DC power supply, and given the circumstances under which the circuit breakers cannot trip. Since the tripping sequence of circuit breakers is detected before the fault occurs, even with dynamic changes of power system conditions, the fault isolation zone can be minimized with lower fault clearance time.

Physical activity or exercise are known to promote bone formation and decrease bone resorption to maintain skeletal and bone health both in animal models and in humans with osteoporosis. Previous studies have indicated that long non-coding RNAs (lncRNAs) are able to regulate bone metabolism. Therefore, the present study aimed to evaluate whether lncRNAs responded to exercise by regulating the balance of bone metabolism in order to prevent osteoporosis. To meet this end, ovariectomized mice were used in the present study to establish an osteoporosis model. The exercise treatment groups were subjected to 9 weeks of treadmill running exercise in 4 weeks of the operation was performed Femurs were collected to measure bone mineral density, bone mass, bone formation and resorption. The expression levels of lncRNAs were subsequently measured using microarray and gene function analyses. The pairwise comparison results [ovariectomy (OVX) vs. OVX + exercise (EX); OVX vs. SHAM; SHAM vs. SHAM + EX; OVX + EX vs. SHAM + EX] of the gene microarray analysis revealed that the expression of 2,424 lncRNAs (1718 upregulated and 706 downregulated) were significantly altered in the mouse femurs following treadmill running. Gene Ontology (GO) analysis, incorporating the GO annotations ‘biological processes’, ‘molecular function’ and ‘cellular components’, of osteoporosis revealed that the VEGF, mTOR and NF-κB signaling pathways were potential targets of the lncRNAs. Moreover, it was possible to predict the target microRNAs (miRNAs) of six lncRNAs (LOC105246953, LOC102637959, NONMMUT014677, NONMMUT027251, ri|D130079K21|PX00187K16|1491 and NONMMUT006626), which suggested that the underlying mechanism by which lncRNAs respond to exercise involved bone regulation via lncRNA-miRNA sponge adsorption. Overall, these results suggested that the treadmill running exercise did regulate lncRNA expression in the bone, and that this was involved in the prevention of osteoporosis.

Exercise is an effective way to prevent osteoporosis, but its mechanism remains unclear. MicroRNAs (miRNAs) play an essential role in bone metabolism. Recently, mechanical loading was reported to induce changes in miRNA expression in osteoblasts. However, the role of miRNAs in bone under exercise and its underlining mechanisms of action still remain unknown. MiR-214 was reported to regulate the process of osteogenesis and is considered a biomarker of osteoporosis. In this study, we aimed to investigate whether exercise could induce changes in miRNA expression in bone and to study the effects of miR-214 on mechanical loading-induced osteogenesis in osteoblasts. The results showed that miR-214 was down-regulated in both tibia from C57BL/6 mice after exercise in vivo and in osteoblasts after mechanical strain in vitro. Mechanical strain could enhance the ALP activity, promote matrix mineralization, up-regulate the expression of osteogenic factors such as ATF4, Osterix, ALP and β-catenin, and down-regulate RANKL and RANK expression. Over-expression of miR-214 not only inhibited the expression of these osteogenic factors but also attenuated mechanical strain-enhanced osteogenesis in osteoblasts. Collectively, our results indicated that miR-214 could attenuate the osteogenic effects of mechanical loading on osteoblasts, suggesting that inhibition of miR-214 may be one of the ways in which exercise prevents osteoporosis.

Physical activity or appropriate exercise prevents the development of osteoporosis. However, the exact mechanism remains unclear although it is well accepted that exercise or mechanical loading regulates the hormones, cytokines, signaling pathways, and noncoding RNAs in bone. Accumulating evidence has shown that bone is a highly vascularized tissue, and dysregulation of vasculature is associated with many bone diseases such as osteoporosis or osteoarthritis. In addition, exercise or mechanical loading regulates bone vascularization in bone microenvironment via the modulation of angiogenic mediators, which play a crucial role in maintaining skeletal health. This review discusses the effects of exercise and its underlying mechanisms for osteoporosis prevention, as well as an angiogenic and osteogenic coupling in response to exercise.

The last circuit breaker (LCB) is the key circuit breaker in the hybrid AC/DC power grids for avoiding severe overvoltage of AC/DC equipment caused by LCBs tripping. A self-adaptive LCBs identification scheme based on the Dijkstra algorithm is proposed. The LCBs identification is formulated as the single-source shortest path problem, which can be solved by the Dijkstra algorithm. If a circuit breaker in the shortest path from each converter valve to the combined AC lines is removed and there are no paths between them, then the circuit breaker can be considered an LCB. The simulation results reveal the effectiveness of the proposed scheme in Hybrid AC/DC power grids for identifying LCBs under different operating modes of AC field.

A unified optimal power flow (OPF) model for AC/DC grids integrated with natural gas systems is proposed for the real-time scheduling of power systems. Herein, the primary physical couplings underlying this coordinated system are modeled and investigated. In addition, the uncertainties of gas loads are considered when studying the role of gas supply for gas-fired units in power system operations. The nonlinear gas system constraints are converted to the second-order cone forms that allow for the use of the Benders decomposition techniques and the interior-point method to obtain the optimal solution. The numerical results of the modified IEEE 118-bus test system that integrates the Belgium 20-node natural gas system demonstrate the effectiveness of the proposed model. The effects of gas demand uncertainties on the optimal schedule of thermal generators are investigated as well.

It is widely accepted that mechanical stress is an important factor in bone associated cell differentiation, including that of mesenchymal stem cells, osteoblasts and osteocytes. The present study aimed to determine the effect of mechanical cyclic compressive load on osteoblast differentiation, and whether this was associated with activation of the wingless‑type (Wnt)/β-catenin signaling pathway. Using a 3D scaffold model, MC3T3‑E1 cells were exposed to cyclic compressive loading via the Flexcell‑5000C™ Compression system. Sinusoidal wave magnitudes of 0.33, 0.5 and 1 MPa were applied for 4, 6 and 8 h, at 1 Hz frequency. Expression levels of genes associated with osteoblast differentiation were enhanced following compression, including alkaline phosphatase, osteocalcin, runt‑related transcription factor 2 and osterix. Optimal compression was observed using a magnitude of 0.5 MPa for 6 h, whereas a magnitude of 1 MPa had no effect on osteoblast differentiation, and had a negative effect when applied for prolonged time periods. Compressive loading additionally enhanced the mRNA expression levels of the Wnt/β‑catenin signaling pathway component, low density lipoprotein receptor‑related protein 5, and the protein expression levels of Wnt1, disheveled segment polarity protein‑2 (DVL2) and β-catenin. By contrast, mRNA expression levels of sclerostin and the inactive form of β-catenin (phosphorylated at Ser33/37/Thr41) were reduced following compressive loading. Following compressive loading of cells, dickkopf-related protein 1 (DKK‑1), an inhibitor of the Wnt signaling pathway, increased protein expression levels of the inactive form of the Wnt‑associated protein, phosphorylated‑β‑catenin, compared with compression alone. However, DVL2 and Wnt1 protein expression levels were unaffected, suggesting that the loading‑induced activation of Wnt/β‑catenin signaling decreased however, it was not prevented by DKK‑1 treatment. In conclusion, the present study demonstrated that cyclic compressive load promoted osteoblast differentiation and may be dependent on the Wnt/β-catenin signaling pathway in regard to magnitude and duration.

The increasing integration of GFUs promotes the coordinated operation of power and gas systems to enhance the system efficiency and reliability. However, the gas inertia characteristic could have imperative impacts on the coordinated scheduling and this property has not been fully studied. This paper proposes a novel multi-period optimal energy flow (OEF) model considering gas inertia and wind power uncertainties for the scheduling and operation of integrated systems. The nonlinear transient natural gas transmission model is reformulated into a linear programming/quadratic programming (LP/QP) model via the reformulation linearization technique (RLT), yielding computational efficiency improvement. The gas inertia is molded as a time delay to study its impacts on the coordinated scheduling. Then, information gap decision theory (IGDT) based risk averse strategy is advocated to deal with the wind power uncertainties and the impact of the uncertainty level is quantified. Extensive simulation results on the modified 6-bus power system with 6-node gas system and the IEEE 39-bus power system integrated with a realistic 20-node natural gas network demonstrate the effectiveness of the proposed method.

There are many lines of evidence indicating that mechanical stress regulates bone metabolism and promotes bone growth. BMP, Wnt, ERK1/2, and OPG/RANKL are the main molecules thought to regulate the effects of mechanical loading on bone formation. Recently, microRNAs were found to be involved in bone cell proliferation and differentiation, regulating the balance of bone formation and bone resorption. Emerging evidence indicates that microRNAs also participate in mechanical stress-mediated bone metabolism, and is associated with disuse induced osteoporosis or osteopenia. Mechanical stress is able to induce expression of microRNAs that modulate the expression of osteogenic and bone resorption factors, leading to the positive impact of mechanical stress on bone. This review discusses the emerging evidence implicating an important role for microRNAs in the mechanical stress response in bone cells, as well as the challenges of translating microRNA research into potential treatment. J. Cell. Physiol. 232: 1239-1245, 2017. © 2016 Wiley Periodicals, Inc.

Modern power grids that have complicated network structures and changeful operating conditions bring challenges to conventional backup protection. A novel fault detection algorithm based on pilot impedances using the synchronized data for transmission line is proposed to improve the sensitivity and reliability of the protection. The novel pilot impedances at both sides of the line are respectively defined by the fault components of positive-, negative-, zero-sequence currents and voltages. The fault judging quantities that fuse pilot impedances are given to establish the protection criterion. The blocking measures are taken to overcome the maloperation problem during power swing and open-phase operation. The proposed algorithm is extensively validated on IEEE 39 bus system and 500 kV two-machine system under various conditions, including internal and external faults, the load encroachment, open-phase operation, power swing and unsynchronized data. The simulation results on PSCAD/EMTDC illustrate that the proposed algorithm can reliably detect the faulted line under various conditions, and have good abilities to resist the fault types, transition resistance, and unsynchronized data.

The last circuit breaker (LCB) protection is applied in hybrid AC/DC power grids to protect the AC/DC equipment from overvoltage threats caused by the unexpected tripping of LCBs. In this paper, an improved Tarjan algorithm is proposed to identify LCBs that correspond to the cut vertices on the path between any two vertices in the connected undirected graph. The proposed method can be applied to multiple converter valves to simultaneously identify the LCBs for each converter valve where all vertices in the connected undirected graph are traversed only once, which significantly improves the running efficiency. The real-time performance of the LCBs identification process was examined on a closed-loop simulation platform based on LabVIEW and MATLAB. The results reveal excellent capabilities of the proposed method for finding LCBs for all converter valves under various conditions of the AC field while exhibiting a lower and more stable runtime.

In order to solve the problem that the fault feature is not obvious for fault section location in non-solidly earthed distribution network, a new fault feature extraction method based on fuzzifying zero-mode current was presented. Zero-mode current signals are acquired by feeder terminal equipment. According to the comparison of the zero-mode current of each equipment and the first feeder terminal equipment, an appropriate fuzzy membership function is constructed to extract the feature of the zero-mode current. And a fuzzy self-correction bat algorithm was presented to solve the problem of fault sections location in distribution network. Based on fuzzy reasoning mechanism, a membership function was established to respond to the own fitness of bats. By introducing the concept of speed factor, bats could modify its value of velocity factor according to the current membership function value in each process of optimization. The algorithm can avoid trapping in local optimum and strengthen the global search ability. Finally the analysis of examples demonstrated the fault sections can be accurately located by using this method and the modified bat algorithm can obviously improve the searching speed.

There is a great improvement in the demand of power with the rapid development of Economic Society. At the same time, safe and stable operation of the grid become the focus of attention. when faults occur in power system, a large number of alarms are sent to the dispatch center, it requires dispatcher judge the faulty component quickly and accurately. In order to improve the accuracy and robustness of power system fault diagnosis, the method of power grid fault diagnosis based on artificial fish swarm algorithm has been proposed. First of all, we have developed the 0–1 integer programming model of the fault diagnosis problem using information from protective relays and circuit breaker. Secondly, we use the Artificial Fish Swarm Algorithm to solve the 0–1 programming problem. And then we have tested the method with some existing numerical example, the simulation results show that the developed mathematical model is correct and the proposed method is suitable and efficient.

Conventional protection relays, which use local signals to locate faults, are a poor fit to modern power grids when compared to communication-based alternatives. This article presents a novel Wide-Area Backup Protection (WABP) algorithm that uses information shared across wide-area communication networks. The WABP algorithm fuses and integrates information in a regional decentralized peer-to-peer negotiation architecture for enhanced effectiveness. Line decision-making agents (LDAs), focused on line-fault detection, collect distance and directional protection information on both sides of a line. If LDAs cannot detect a fault locally, wide-area information that includes directional protection and line-fault states from neighboring lines is collected to locate the fault. The LDA considers the possible presence of relay misoperations, protection failures, and/or communication failures. Regional decision-making agents (RDAs) that reside in a regional decision-making device (RDD) in the monitoring layer of a substation can negotiate in a peer-to-peer manner without a control center. The RDA serves as the manager, coordinator, and message transponder for the LDAs. The design of the WABP is described including its architecture, workflow, and its agents' functions. Simulation scenarios illustrate the correctness of the WABP multi-agent system and the higher fault-tolerance of its response to misoperations, protection failures, and communication failures.

There are many lines of evidence indicating that mechanical stress regulates bone metabolism and promotes bone growth. BMP, Wnt, ERK1/2, and OPG/RANKL are the main molecules thought to regulate the effects of mechanical loading on bone formation. Recently, microRNAs were found to be involved in bone cell proliferation and differentiation, regulating the balance of bone formation and bone resorption. Emerging evidence indicates that microRNAs also participate in mechanical stress-mediated bone metabolism, and is associated with disuse induced osteoporosis or osteopenia. Mechanical stress is able to induce expression of microRNAs that modulate the expression of osteogenic and bone resorption factors, leading to the positive impact of mechanical stress on bone. This review discusses the emerging evidence implicating an important role for microRNAs in the mechanical stress response in bone cells, as well as the challenges of translating microRNA research into potential treatment. J. Cell. Physiol. 232: 1239-1245, 2017. © 2016 Wiley Periodicals, Inc.

The safe and reliable operation of Smart substations based on IEC 61850 is faced with new challenges because of the free distribution of functions, it's critical to carry out risk assessment of secondary system of smart substation. Based on the concept of function decomposition, secondary system is considered as the assembly of a series of closely linked functions. Structure entropy weight method is used to define the weight of every function. Taking account that the reliability of elements varies with operation time, the temporal behaviors of all functions risk are obtained, providing theoretical guidance for smart substation management.

It's significant to make an efficient scheme about fault diagnosis on account of the closer interconnection of regional power grids and the complex structure of the system. The traditional fuzzy C-means algorithm (FCM) ignores different contribution between different types of data and the class edge is fuzzy. In view of these problems, this paper presents a new method about fault diagnosis for power grid based on adaptive improved FCM algorithm. This method which can effectively distinguish the contribution from different fault information during the clustering process uses multi-source data and overcomes defects of traditional FCM algorithm as well. The simulation results show that this algorithm can complete fault diagnosis accurately and quickly.

At present, the checking and designing of SCD's virtual terminal in smart substation are used by hand, and their rationalities are not easy to be verified. This paper studied a kind of searching and analyzing method of device virtual links based on historical SCDs. The virtual links are extracted from a number of existed SCDs, and stored into the database as the templates. For the SCD's receiving device and sending device, the two device names are used to form a related pair code. Using the technologies of virtual link table's redundant fields and multi-hash tables, the same related pair and their virtual links are fast queried from the history of SCD database. Comparing original related pair's virtual links with those same related pair's virtual links, the most similar related pair is obtained. The SCD with maximum same number of IEDs can be searched as best similar SCD as another searching mode. The paper gives the search results of each related pair. Qt and C++ is used to develop the searching and analyzing tool. It has been applied to virtual links analysis for a practical SCD of smart substation. It can save the analyzing time and improving the intelligence of system testing.

The conventional protection relays based on local signals, can be greatly enhanced in modern power grids. This article proposes a novel two-stage hybrid online fault detection algorithm based on wide-area protection and limited PMUs by wide-area communication network. In first stage, the wide-area algorithm calculates the lines' relative fault degrees on wide-area backup protections. After sorting the lines by relative fault degrees, the faulted lines can be detected directly or most two suspected lines with highest relative fault degrees can be identified. When main and backup protection fails to act on faulted line, maloperation protections occur on normal line, or two faults occur on adjacent lines, the algorithm for fault lines may fail. In the second stage, the algorithm uses multiple groups of PMUs to accurately detect the fault positions. By fusing the PMU data, the hybrid algorithm can correctly detect faults under diverse scenarios. The on-line fault detection algorithm has been implemented in simulation to demonstrate its effectiveness. The fault tolerance of the system is improved, particularly in the presence of multiple protection errors and device failures. The simulation scenarios illustrate the correctness of two-stage hybrid online fault detection method.

This paper focuses on the modeling and verification of a peer-to-peer wide-area backup protection (WABP) system. Agents located in a number of substation intelligent electronic devices (IEDs) negotiate on a peer, or equal, basis. The agent-based wide-area backup protection scheme is able to find power-line faults and protection misoperations. A wide-area communication network based on IP technology is used to transmit shared information among the agents. A novel agent-oriented peer-to-peer negotiating colored Petri net (AOPCPN) is proposed to implement the WABP system. The algorithms, design, and dynamic behavior of the WABP is evaluated in a simulated environment to demonstrate its benefits. The article begins by presenting the generic AOPCPN architecture and its formal definition. The AOPCPN model for the WABP multiagent system is evaluated according to one algorithm, which is detailed in this article. The WABP agent's autonomy, cooperation, parallel operation, and robustness are embodied in modules in order to ease the software engineering challenges in implementing and maintaining the agents. Three example scenarios illustrate the effectiveness of the Petri net model and its ability to dynamically respond to WABP misoperations and fault conditions.

The control systems in current and future power systems need reliable real-time information transmission. Internet Protocol (IP) based communication systems for wide-area frequency stability predictive control systems are proposed in this paper. The key technologies, such as network topology, communication protocols, and communication modes are studied. The frequency stability predictive control algorithm need the wide-area measurements sampled in plants and substations to be transmitted to a main control node and load shedding commands to be sent to substations from the main control node. A modified IEEE 50-generator test system equipped with the proposed wide-area frequency stability predictive control is established and simulated using the electric power and communication synchronizing simulator (EPOCHS). PSS/E is combined the Network Simulator 2 (NS2) in the EPOCHS simulation environment. The simulation results show the effectiveness of the proposed communication system.

The wide-area communication network (WAN) has become fundamental support for wide-area control systems in power system. A co-simulation extending for WAN has been studied to provide the communication interfaces to and from OPNET. The co-simulation framework includes the demand side (the control systems based on WAN), co-simulation module (cosim), OPNET and its extended modules. The key technologies are studied, such as the external system module (esys) in OPNET, a virtual UDP application connecting esys to UDP layer, cosim, and the exchange mode between communication demand side and cosim. The implementation of prototype system is given. The simulation testing illustrates the effectiveness of the extending working. It will provide a reference for the simulation in other control systems with WAN in power system.

In order to meet the requirements of cooperation and information sharing with different layers among some heterogeneous subsystems in power system, a wide-area cooperation multi-agent platform is proposed based on Web service and agent technology. The wide-area cooperation model is discussed firstly; the principles of the framework implementing the platform are expatiated. Some key technologies are studied, such as the design pattern of diagnostic agent, the implementation of web service components, and the negotiation mechanisms based on business event and publish/subscribe. The design and implementation of the prototype for wide-area backup protection in power system illustrate that the platform can provide bidirectional communication for wide-area cooperation agents and greatly improve the intelligence and flexibility of distributed system.

Agent-based wide-area backup protection (WABP) systems have been studied to improve the security of power system in recent years. IEC61850 has become an approved international communication standard for substation automation system. In order to make WABP device conform to the developing of substation automation system, the information model of wide-area backup protection based on IEC61850 is proposed in the paper. According to a kind of WABP algorithm, a decentralized and distributed architecture of WABP multi- agent system is given, in which the negotiation between protection agents is peer-to-peer manner. The WABP agent residing in protection IED (Intelligent Electronic Device) is regarded as a special logical node. The collaboration relations and information flows between WABP agent and conventional logical nodes are analyzed. The functions of WABP IED can be divided to three layers: interface layer, advanced process layer and basic computing layer. The remote message transferring principle for WABP agent in different substations is studied. The negotiation messages, which include staged distance protection actions, synchronous current signals and the fault judgments for transmission line, are organized with GOOSE or SAV. HDP or TCP is adopted to transmit the messages among the substations according to the types of messages. The communication agent in communication manager machine is responsible for forwarding remote messages from/to WABP IED. The information model for WABP agent has been designed and validated in EPOCHS platform. The work may provide a reference for the developing of wide-area protection device.

A partially blind signature allows a signer to explicitly embed a pre-agreed common information into a blind signature without the loss of blindness property. It is an important technology in e-commerce. In ID-based public key setting, a user's public key can be derived directly from his identity without access to public key certificate. It can simplify the key management process in traditional certificate based cryptosystem. To our knowledge, many partially blind signature schemes have been proposed till now. However, no ID-based partially blind signature scheme has been proposed. Recently, Chow et al. first proposed an ID-based partially blind signature scheme based on bilinear pairings, but it isn 't very efficient. In this paper, we improve C how et al's scheme and present a new ID-based partially blind signature scheme. We also analyze the security and efficiency of the proposed scheme. We show that our scheme is more efficient and needs less computation cost than Chow et al.'s scheme and is provably secure under the random oracle model.

The wide-area backup protection algorithms based on multi-agent have been developed during recent years. Based on these known algorithms, the cooperative modeling and design mechanism of multi-agent is studied to construct novel protection system in this paper. The abstract concept and principle of the agent are embodied; organization-based collaboration of multi- agent is proposed to improve the protection system's intelligence and abilities of eliminating the misoperation and reject of protection. Some design mechanisms of the agent are given for the wide-area backup protection, such as agent's internal three- layer structure, functional modules, equal organizational structure, the negotiation protocol, and three fault-tolerance measures. The state diagram and collaboration diagram are adapted to analyze interaction behaviors among agents. An example is given to explain the negotiation procedure while all protection operations in an agent are failing. Another example explains how multiple agents cooperate to find and lock the misoperation of III line protection made by transmission line overload. These examples illustrate the reasonableness of the design mechanism of the agent.

With the development of high speed railways, there are higher requirements to insure the reliability of the traction power supply system. In this paper, a novel insulation on-line monitoring and fault diagnosis system based on the embedded Linux operation system is introduced. The system can continuously monitor the insulation state of the power instruments, such as traction transformers, arresters, circuit breakers, and insulators. Different monitoring techniques were applied in the system. The embedded Linux operation system with TCP/IP protocol makes the field monitoring devices possess the powerful data processing and networking functions. The monitoring system builds a good basis for traction substation insulation on-line monitoring and diagnosis.