Reachability analysis of web service compositions via NWA

In order to improve the design and implementation quality of web service compositions,formal methods are used to model them and certain properties are verified.WCFA （web service interface control flow automata）is used to model web services,especially the control flow and possible interactions with other web services.A web service composition consists of a set of interacting WCFA.The global behavior of web service compositions is captured by NWA（nested word automata）.A variation of the depth-first search algorithm is used to transform a set of WCFA into an NWA.State formulae and call stacks at each node of NWA are computed by a path-sensitive reachability analysis.Safety properties,call stack inspection properties and pre/post-conditions of service invocations are described by assertions.Then verification of these assertions is carried out by an automated SAT tool.

Using modified Soil Conservation Service curve number method to simulate the role of forest in flood control in the upper reach of the Tingjiang River in China

To improve flood control efficiency and increase urban resilience to flooding,the impacts of forest type change on flood control in the upper reach of the Tingjiang River(URTR) were evaluated by a modified model based on the Soil Conservation Service curve number(SCS-CN) method. Parameters of the model were selected and determined according to the comprehensive analysis of model evaluation indexes. The first simulation of forest reconstruction scenario,namely a coniferous forest covering 59.35km^2 is replaced by a broad-leaved forest showed no significant impact on the flood reduction in the URTR. The second simulation was added with 61.75km^2 bamboo forest replaced by broad-leaved forest,the reduction of flood peak discharge and flood volume could be improved significantly. Specifically,flood peak discharge of 10-year return period event was reduced to 7-year event,and the reduction rate of small flood was 21%-28%. Moreover,the flood volume was reduced by 9%-14% and 18%-35% for moderate floods and small floods,respectively. The resultssuggest that the bamboo forest reconstruction is an effective control solution for small to moderate flood in the URTR,the effect of forest conversion on flood volume is increasingly reduced as the rainfall amount increases to more extreme magnitude. Using a hydrological model with scenarios analysis is an effective simulation approach in investigating the relationship between forest type change and flood control. This method would provide reliable support for flood control and disaster mitigation in mountainous cities.

Thruster direction controlling of assembled spacecraft based on gimbal suspension

The attitude control system design and its control effect are affected considerably by the mass-property parameters of the spacecraft. In the mission of on-orbit servicing, as fuel is expended, or the payloads are added or removed, the center of mass will be changed in certain axe; consequently, some thrusters＇ directions are deviated from the center of mass（CM） in certain plane. The CM of assembled spacecraft estimation and thruster direction control are studied. Firstly, the attitude dynamics of the assembled spacecraft is established based on the Newton-Euler method. Secondly, the estimation can be identified by the least recursive squares algorithm. Then, a scheme to control the thrusters＇ directions is proposed. By using the gimbal installed at the end of the boom, the angle of the thruster is controlled by driving the gimbal; therefore, thrusters can be directed to the CM again. Finally, numerical simulations are used to verify this scheme. Results of the numerical simulations clearly show that this control scheme is rational and feasible.

Frequency control ancillary service provided by a wind farm:dual-BESS scheme

Network frequency control function is incorporated into a grid-connected wind farm-dual battery energy storage system(BESS)scheme.The design of the scheme takes advantage of the rapid response characteristics of the BESS and the in-built short-term overloading capability of the associated power conversion devices.A control strategy to regulate the BESS output power is then proposed.It is shown that the frequency control action offered by the BESS complements amicably with that of conventional generators in enhancing the frequency regulation attribute of the grid system.

The Service Utility Model in Service Management

Aiming to provide a measurable service Quality of Service （ QoS） evaluating method for service inventory management, this paper proposes a new mobile Service Utility Model （SUM）, considers the service and business layer elements into the service utility influence profile, and proposes an self-adaptive service inventory management algorithm as a QoS control scheme based on SUM. It can be concluded from the simulation result that the service inventory utility can be fully reflected by SUM and the whole system efficiency is greatly increased by using SUM as the adaptive rule.

Heat Pumps in Denmark:Current Situation in Providing Frequency Control Ancillary Services

-The Danish government set an ambitious goal to achieve a fully renewable-based energy system by 2050.In this context,the integrated electricity and heating system is undergoing rapid development in Denmark as a promising way to accommodate the ever-growing renewable energy sources(RESs).The electric heat pumps(HPs),coupled with the power and heat sectors,can propagate the flexibility on the heat consumer side to the power system operations,playing an important role of improving system flexibility and balancing the variability of the RES.In this paper,the current development situation of HPs in Denmark is analyzed,including both the large-scale HPs in the district heating system and individual HPs on the residential side.The possibility of using HPs to provide frequency control ancillary service(FCAS)is analyzed according to the market and technical requirements of the FCAS in the Danish transmission system and experimental results of representative demonstration projects of HPs.A comprehensive analysis of the advantages,barriers,future prospects,and challenges for using HPs to provide the FCAS are carried out from the perspectives of different entities.

On SCP Overload Control in Mobile Intelligent Network Based on Queue Size

For there is no overload control signal between Service Switch Point and Service Control Point at CALEL 2 stage of mobile intelligent network, we provide an overload control algorithm realized in SCP. In the algorithm, we use a leaky bucket controller in access module to filter user calls and set an appropriate finite buffer in SCF module for protection further. The results of analysis and simulation indicate that by making the call arrival rate to SCF module equal its service rate when SCP become overloaded, the call processing rate of SCP system can keep its optimal value.

Effects of crop species richness on pest-natural enemy systems based on an experimental model system using a microlandscape

The relationship between crop richness and predator-prey interactions as they relate to pest-natural enemy systems is a very important topic in ecology and greatly affects biological control services.The effects of crop arrangement on predator-prey interactions have received much attention as the basis for pest population management.To explore the internal mechanisms and factors driving the relationship between crop richness and pest population management,we designed an experimental model system of a microlandscape that included 50 plots and five treatments.Each treatment had 10 repetitions in each year from 2007 to 2010.The results showed that the biomass of pests and their natural enemies increased with increasing crop biomass and decreased with decreasing crop biomass;however,the effects of plant biomass on the pest and natural enemy biomass were not significant.The relationship between adjacent trophic levels was significant(such as pests and their natural enemies or crops and pests),whereas non-adjacent trophic levels(crops and natural enemies) did not significantly interact with each other.The ratio of natural enemy/pest biomass was the highest in the areas of four crop species that had the best biological control service.Having either low or high crop species richness did not enhance the pest population management service and lead to loss of biological control.Although the resource concentration hypothesis was not well supported by our results,high crop species richness could suppress the pest population,indicating that crop species richness could enhance biological control services.These results could be applied in habitat management aimed at biological control,provide the theoretical basis for agricultural landscape design,and also suggest new methods for integrated pest management.

Dynamic data packing towards the optimization of QoC and QoS in networked control systems

A class of networked control systems is investigated whose communication network is shared with other applications. The design objective for such a system setting is not only the optimization of the control performance but also the efficient utilization of the communication resources. We observe that at a large time scale the data packet delay in the communication network is roughly varying piecewise constant, which is typically true for data networks like the Internet. Based on this observation, a dynamic data packing scheme is proposed within the recently developed packet-based control framework for networked control systems. As expected this proposed approach achieves a fine balance between the control performance and the communication utilization: the similar control performance can be obtained at dramatically reduced cost of the communication resources. Simulations illustrate the effectiveness of the proposed approach.

Traffic Source Characterization：Considering Real Demands of Communication Attempts

in order to project a reliable telecommunication network ,we have to measure the call lossrate of present traffic and to predzct the traffic of hajective network. In this paper we point out that afactor of real communication needs for subscrihas should be added in studying the traffic source char-acterization. Generally, the predicted traffic does not equal to the real demends, Considered asubscriber's psychological facter for attempts in busy-hour, a mathematical medel of probable dertva-tive calls from each real communication demand is given,with which the calling-up probabity, andthe repeating attempt probability of original subscribers on line occupation are calculated and the rela-tionship between the traffic and the real cammunication need is predicted.

Double LSTM Structure for Network Traffic Flow Prediction

The network traffic prediction is important for service quality control in computer network.The performance of the traditional prediction method significantly degrades for the burst short-term flow.In view of the problem,this paper proposes a double LSTMs structure,one of which acts as the main flow predictor,another as the detector of the time the burst flow starts at.The two LSTM units can exchange information about their internal states,and the predictor uses the detector’s information to improve the accuracy of the prediction.A training algorithm is developed specially to train the structure offline.To obtain the prediction online,a pulse series is used as a simulant of the burst event.A simulation experiment is designed to test performance of the predictor.The results of the experiment show that the prediction accuracy of the double LSTM structure is significantly improved,compared with the traditional single LSTM structure.