Software evolution is a fact of life. Over the past thirty years, researchers have proposed hypotheses on how software changes, and provided evidence that both supports refutes these hypotheses. To paint clearer image process, we performed an empirical study long spans in lifetime seven open source projects. Our analysis covers 653 official releases, combined 69 years evolution. We first tried to verify Lehman's laws findings indicate several are confirmed, while rest can be either confirmed...

Due to the high R/X ratio and mismatched feeder impedance of low-voltage microgrids, conventional droop method is no longer able decouple active reactive power distributed generators powersharing accuracy degraded. In this article, a virtual complex based P - V̇ proposed powers improve power-sharing among DGs. With method, equivalent between source point common coupling shaped be purely resistive. Then, strategy adopted alleviate effect line impedance, where rather than ordinary P/Q are used...

Due to the dust deposition on surface of photovoltaic modules and air pollution, power generation performance will be significantly affected. In order quantitatively estimate effect quality modules, a distributed system building roof in Shanghai is studied this paper. Both artificial natural conditions are tested terms influence these factors efficiency modules. The variation solar radiation intensity with PM2.5 concentration module capacity analyzed. experimental results show that reduces...

By means of advanced information and communication technology, cyber‐physical power systems can attain real‐time monitor control but have to suffer the damage caused by a cyber attack. In this study, authors' define attack efficiency evaluate paths that attacker may adopt intrude systems, find most efficient (i.e. vulnerable paths). Based on actual grid security stability system, coupling model is established analyse propagation cascading failure within across physical network. model, cost...

Solar PV generation is widespread in the distribution system nowadays, and high-penetration brings challenges to reliable grid operation. Taiwan's government has set a policy goal of achieving 20% total electricity from renewable sources by 2025. However, intermittent unpredictable nature energy leads voltage deviation overvoltage buses. Nevertheless, increasing capacity feeders crucial 2025 target. This study employs stochastic analysis method simulate hosting accommodated feeder. The...

The negative ion air purifier (NIAP) has been used for capturing particulate matter. Nevertheless, the knowledge on its effectiveness in removing other pollutants such as ammonia gas remains limited. In this study, effect of an NIAP indoor removal was evaluated through a series experimental studies. applicability and different influencing, operating, environmental factors performance were firstly investigated by conducting experiments. Then, order to understand spatial distribution...

Abstract JZS Oilfield is an offshore metamorphic rock fractured buried hill oilfield. It was put into development in July 2010.The overall production situation of the oilfield good, but some problems have been exposed. The main performance as follows: difference water cut rise characteristics and poor fitting wells affect prediction accuracy remaining oil adjustment exploitation potential To solve above problems, a set fine geological modeling method dual-medium reservoir based on BP neural...

SUMMARY Software evolution is a fact of life. Over the past 30 years, researchers have proposed hypotheses on how software changes and provided evidence that both supports refutes these hypotheses. To paint clearer image process, we performed an empirical study long spans in lifetime nine open‐source projects. Our analysis covers 705 official releases combined 108 years evolution. We first tried to confirm Lehman's eight laws projects using statistical hypothesis testing. findings indicate...

Multi-functional grid-tied inverters (MFGTIs) have been investigated recently for improving the power quality (PQ) of microgrids (MGs) by exploiting residual capacity (RC) distributed generators. Several centralized and decentralized methods proposed to coordinate MFGTIs. However, with increasing number MFGTIs, it demands a method improved reliability flexibility, which are characteristics framework that has not introduced into PQ improvement (PQI) field before. In this paper, we propose...

In this letter, an electrowetting fabrication technique for the production of lenses is proposed. The unique capability controlling lens profile during processes successfully demonstrated. involves use electrically conductive ultraviolet (UV)-curable polymer and phenomenon. control achieved by adjusting voltage across a hydrophobic dielectric layer sandwiched between UV-curable (the liquid) substrate electrode), thereby introducing different degrees For fabricated on Teflon layer, it found...

Due to the high resistance/reactance (R/X) ratio of a low-voltage microgrid (LVMG), virtual complex impedance-based <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$P-\dot {V}/Q-\omega $ </tex-math></inline-formula> droop control is adopted in this article as primary (PC) technique for stabilizing system. A distributed event-triggered restoration mechanism (ETSM) proposed secondary (SC) restore...

This article proposes a distributed event-triggered control method for multifunctional grid-tied inverters (MFGTIs) in microgrid to improve power quality under denial-of-service (DoS) attack. The proposed tackles two key challenges. first is dynamic adjustment of inverter residual capacities responding variations the accessible renewable and harmonic unbalanced current. second DoS-resistant with following specific functional requirements improvement task. 1) Quantitative characterization...

The technology of multimedia Content Delivery Network (CDN) is to build some replica servers in the network. origin server replicates contents these order reduce loading and utilization bandwidth. client issues a request most appropriate instead server, which can provide same contents. main function routing system CDN redirect client's server. Some popular algorithms include random choice, round robin, depending on bandwidth availability, hard disk connection availability. In this paper, we...

The dispatcher-based Web server load balancing architecture can improve the performance of popular servers. When backend servers have different computational power, system must use real-time loading information as decision making criteria. In this paper, we proposed a dispatcher that uses remaining capacity each to decide most appropriate server. addition performance, also algorithm reduce cost when side does not frequent burst request. For example, course registration ticket reservation...

University libraries are usually high energy consuming buildings on campus and the operation efficiency of air conditioning system is still far from satisfactory. Combined with building automation technology, heating, ventilation air-conditioning (HVAC) control for university library has been proposed via fieldbus communication. The analysis electrical technology field presented because traditional automatic design cannot reflect relationship between electronic devices in detail....

This article considers the distributed resilient cooperative control for photovoltaic generators (PVs) suffered from two types of denial-of-service (DoS) attack, where global DoS attack jams all communication channels and one each independently. The proposed method realizes fair utilization PVs, restore active power flow across certain transmission line voltage critical bus to their reference values. self-triggered mechanism is introduced ensure performance under reduce data in network...

A micro grid consists of several distributed generation resources and local loads, which provide the solution to supply premium power remote or specific areas. To design a grid, it is necessary perform computer simulation for planning study. Before actual system built, all potential responses should be known then can modified avoid negative impacts system. This paper presents experiences modeling simulations observing connected ac faults on dc grid. Results study are also reported.

Multimedia Content Delivery Networks (CDN) is used to improve the performance and reliability on Internet. In CDN architecture, multimedia contents are replicated from origin server replica servers in order minimize use of network bandwidth. Efficient placing a challenging problem. There five factors that can be determine placement contents, they bandwidth availability, connection storage CPU memory availability. this paper, Particle Swarm Optimization (PSO) algorithm adopted solve issue....

In this design, the air source heat pump temperature process control system test device is taken as research background, and insulation water tank object, studied. Because traditional susceptible to external interference, stability reliability of circuit design are relatively poor. Aiming at these disadvantages, an intelligent based on STCS9C52 single-chip microcomputer designed. According established mathematical model, fuzzy theory combined with PID controller realize parameter adaptive...