6 Suggested Future Work
The investigation of the defects, their root cause and their effects is being done by researchers all over the world. The mechanisms behind the degradation modes in the solar cell semiconductor material need further research. The Potential Induced Degradation (PID) is a relatively new degradation mode first reported in 2010 by Pingel et al. (2010). The origin of the sodium accumulated at the shunts, defects and at the junction is still not confirmed and deserve further investigation. Additionally, the module analyzed in this study presented corrosion areas with different colorations which could indicate different degradations modes. The analysis of these spots can provide insights about the effects of agging in a wheather like Rochester, humid and where the temperature varies broadly along the year. Regarding the mathematical model, the development of a model using the two diodes equation, taking into account the aging effects, can provide an accurate prediction of the photovoltaic systems under service for longer time.
86 3.3.1. Introduction
One of the main difficulties involved in monitoring systems is the inability to add new devices or new ways of evaluating the performance of these systems without significantly changing the topology of the monitoring system. Firstly, the incorporation of new devices, in the absence of standard communication protocols, requires the development of software for acquiring data from these devices and it is also necessary to add the functionality of each of the data that are acquired. Moreover, in photovoltaic (PV) plants connected to the grid each inverter has its own communication protocol and issues its own program online or locally to access data and plant information. These programs do not allow the inclusion of data from other inverters or for other plants even in the case of inverters from the same manufacturer. Also, it is not possible to incorporate any functionality to them in order to make a diagnosis and evaluation of the operation of facilities, beyond including the system supplied by the manufacturer of the inverter, who usually simply presents the information of the recorded data. Therefore, it is possible to ensure that one of the most important problems when it comes to monitoring and supervising solar energy plants is the communication between devices due to the different types used. It is common to find many devices of different types and manufacturers who use different ways of communication. In order to obtain a generic system, a general mechanism is needed to communicate with any devices, irrespective of their characteristics or of the manufacturer.
In this paper, we carried out several experimental performance comparisons between the IPv4 and IPv6 protocol stack on the operatingsystems including Windows XP, Windows 7 and Fedora 12 over Peer- to-Peer 802.11n WLAN with no security added. At the time of this research, Windows 7 was the operating system most widely used by most companies. Using TCP and UDP throughput and round-trip time as the metric, our experimental results show that, for all the three operatingsystems, IPv4 outperformed IPv6 on most packet sizes for both TCP and UDP traffic. Although IPv6 has many advantages, it also has its drawbacks by having lower bandwidth and higher delay compared to IPv4 due to IPv6 larger header size.
Abstract— Cloud computing has simply means Internet Computing. The Internet is commonly visualized as clouds. Hence the term cloud computing for computation done through the Internet. With Cloud computing users can access database resources via the Internet from anywhere. Cloud computing provides the facility to access shared resources and common infrastructure, offering services on demand over the network to perform operations that meet changing business needs. The virtualization of IT infrastructure enables the consolidation and pooling of IT resources so that they can be shared over diverse applications. With the help of virtualization logical abstraction of physical resource is possible which is very lucrative for the IT business. Thus we can save the capital of IT business. Virtualization is very important for cloud computing because the delivery of services is simplified by providing a platform, infrastructure and services for optimizing complex IT resources in a feasible manner, which makes cloud computing more cost effective. This paper presents PerformanceAnalysis of Various Guest OperatingSystems on Ubuntu 14.04.Various Guest OS performance on Ubuntu cloud of different virtual machine of Ubuntu and WinXP’s performance in the CPU Time, Memory usage, and percent CPU usage in the KVM hypervisor virtualization. Our comparison was carried using Libvirt tool kit commands result and sysbench benchmark tool. Our goals are that how the different virtual machine of single host affects the performance and make informed decision about choice of best virtual machine indication to the cloud guest OS on Ubuntu.
Cells will also exhibit long-term degradation if the temperature exceeds certain limit [7, 8]. The cell manufacturer will generally specify a given temperature degradation coefficient and a maximum operating temperature for the cell. The cell efficiency is known to decrease due to non-uniform temperatures across the cell [9, 10]. In a photovoltaic module, a number of cells are electrically connected in series, and several of these series connections can be connected in parallel. Series connections increase the output voltage, while the parallel connection increases the current. The aim of this paper is to study the effect of temperature on performance of PV system operating under concentration to get solutions to minimize the cost of 1kwh.
The file sizes used in the experiment were divided into ranges of typical textual content, smaller and larger im- ages, as well as large video files. The research aims to show to what extent and in what way the choice of an oper- ating system affects the performance of the site. Other characteristics of the architecture of the web server on which the web site is hosted and executed are unchanged so that they cannot affect the measurement results. To ensure virtually unchanged conditions regarding other features of this experimental platform, such as local net- work connection speed, the experiment was performed on a local network, thus excluding network capacity as a possible bottleneck of the model. This reduces the im- pact of changing the speed of the Internet connection due to changes in the connection load at different times of the day . The web site was loaded from a local server exclusively purposed for the experiment. For both operating system families, the same computer was used as the server, each in term. The computer from which the content download request was made was discon- nected from the Internet connection during the experi- ment. Also, all installed programs were turned off dur- ing the measurement. In this way, the influence of other software on the measurement results for the duration of the experiment was reduced. In the study, we tested the effects of systems from the two most commonly used families of server operatingsystems - Windows and GNU/Linux distributions  . In the case of Win- dows, the latest version at the time of the research was
1,2 Department of Electrical & Electronics Engineering
1 Institute of Road & Transport Technology, Erode 2 SriRamakrishna Engineering College, Coimbatore
Abstract— The Photovoltaic (PV) systems are trending in power sector area due to their eco-friendly nature. This article emphasizes on constructing a PV module, based on individual diode type and simulating it in MATLAB/SIMULINK. The performance of the module for changing conditions of radiation, temperature, series resistance and ideality factor are explored. The influence of these parameters on the Maximum Power output, Efficiency and Fill Factor are studied for Solkar 36W PV module.
monitoring vendors that integrate software and hardware in order to provide better customer service. In that way a large amount of high-resolution data is uploaded daily on web platforms and is available to the public.
The online service of Solar-Log was used, as it is one of the key players in monitoring with more than 80,000 system owners using the service. Also, it is one of the very few companies that offer free access to the users’ web platform. The web-scraping software that was developed in this task in order to extract online data was able to simulate human navigation through web sources, to locate and save scattered information that was available to the user, and finally to organize that information in datasheets. In this way, daily yields (AC and DC) and all the operational details from 2914 systems in the Netherlands, Germany, Belgium, France and Italy were collected.
The performance of PV system under non uniform irradiance and partial shading condition is analyzed with help of conventional perturb and observe method and improved Incremental Resistance algorithm. The outputs are generated using MATLAB/SIMLUNK. Partial Shading of modules is given importance in this work. The Perturb and observe method is evaluated along with fuzzy controller and the output of the system is compared with Incremental Resistance method. The system with fuzzy logic controller was found to be more efficient and attains stability much faster than any other controller. But the power output of system with INR method was found to be more stable and with boosted value. The comparison of the two MPPT schemes is done in this paper and the performance of the schemes is analyzed.
Sydney Institute of Business and Technology, Western Sydney University, Sydney City Campus, Australia
The energy assessment of the PV power systems is carried out by using dif- ferent types of performance indicators that benchmark the output of these systems against the PV panel maximum output at hypothetical operation conditions. In this paper, a comparative analysis of six types of performance indicators is conducted and a new performance indicator which considers PV panel slope and orientation is proposed. The proposed indicator is bench- marking the PV system actual output against the maximum output of the same system if it would operate in two axis tracking mode. The proposed per- formance indicator is used to develop a friendly user calculator of PV system output that can be used by, energy providers and PV system installers to evaluate the output of the PV grid connect network. The advantage of the de- veloped calculator is highlighted by a case study that estimates energy capacity of different residential rooftop PVsystems installed in a residential suburb in Sydney.
Conventionally, grid is a combination of large generating units operated by utilities, many operating engineers, maintenance mans. With expansion of electrical network, it has become hard for the engineer to review generators connected to grid against any kind of fault. With electrical network moving towards decentralized generation, it may even be hard to monitor the running status of all small, medium and large power generators, especially with roof top installed PV and wind based grid tied generator. Real problem appears when an electrical network is taken down for some maintenance by either shutting down the large and medium capacity generator or by opening the circuit breakers of feeding or transmission lines connected.Even then small capacity distributed power generators may keep on supplying the power to grid. It may result hazardous for maintenance crew unaware of such generator being online.Inverters which are operating in parallel while connecting to the grid will work as current sources used to supply power to the utility grid. The grid connected inverters supply power to the grid as
Therefore, the standards in the power quality area are devoted to maintaining the supply voltage within certain limits.
AC power systems are designed to operate at a sinusoidal voltage of a given frequency [typically 50 hertz in India] and magnitude. Any significant deviation in the waveform magnitude, frequency, or purity is a potential power quality problem.
Limmnios presented a general model for dependability measures for continuous and discrete time semi-Markov processes. Author has proposed various theorems and Lemma to derive the dependability measures. The paper is limited to the theoretical and analytical treatment only .
Markovian models and their analysis techniques accomplish an important function in evaluating reliability/availability in complex engineering systems. Markovian modeling is essentially associated with constant rate of transition from one state to another state of the system and is strictly applicable to exponential distributions. When a more general form for the distribution of a system component failure or repair is considered, a non Markovian process takes place. In their study the approach of the method of stages is analyzed, provided that, offers a great potential applicability to solve industrial problems. An application, for the Chilean copper mining sector is presented, since these modeling methodologies can optimize the activities of maintenance and production in this sector .
* Correspondence: firstname.lastname@example.org; Tel.: +34-987 29 10 00 - 5391.
Abstract: It is well known that working PV plants show several maintenance needs due to wiring and modules degradation, mismatches, dust and PV cells defects and faults. There are a wide range of studies that show the theoretical and some laboratory tests of how these circumstances may affect the PV production. Thus, it results mandatory to evaluate the whole PV plant performance and, then, it’s payback time, profitability and environmental impact or carbon footprint. However, very few studies include a systematic procedure to quantify and supervise the real degradation effects and faults impacts on the field. In this paper, the authors first conduct a brief review of the most frequent PV faults and degradation that can be found on real conditions operative PV Plants. Then, they propose and develop an innovative Geographic Information System application to locate and supervise them. The designed tool has been applied to either a large PV plant of 108 kWp and a small PV plant of just 9 kWp installed on a home rooftop. For the large PV plant, 24 strings of PV modules have been modelized and introduced into the GIS application and every module in the power plant has been studied including voltage, current, power, series and parallel resistance, fill factor, normalized PV curve to STC, thermography and visual analysis. For the small PV installation 3 strings of PV panels have been studied identically. It must be noticed that PV modules in this case include power optimizers. The precision of the study allows the researchers to locate and supervise up to a third part of every PV cell in the system, which are adequately georreferenciated. The developed tool allows both the researchers and the investors to increase control on the PV plant performance and conducts to a better planification of maintenance actuations and to evaluate several PV modules replacement strategies in a preventive maintenance programme. Found PV faults include hot spots, snail tracks, EVA discoloration, PV cells fractures, busbars discoloration, bubbles and Si discoloration.
Other monitoring approaches are based on performance indicators calculated through electro- thermal modelling techniques of the PV plant . As these indicators are calculated on a daily basis, thus they are also do not result effective for our purposes.
On the other hand, the latest data acquisition systems that have been integrated on the supervision and monitoring devices for photovoltaic plants are based on wireless technology such as “Zigbee”, according to IEEE 802.15.4, based specification for personal area networks. Parameters such as temperature, irradiation, DC power input in the inverter and AC power output to the grid can be easily obtained. Furthermore, these acquired data can be uploaded to the cloud almost in real time and send notification alerts to the power plant owners and maintenance servicemaintainers . However, these systems still do not integrate georreferences tools that may help to improve the application of a preventive maintenance strategy.
AP, Department of Computer Science, Baba farid College, Bathinda (Punjab)
2 AP, Department of Computer Science, Shah Satnam Ji P.G Boys College, Sirsa (Haryana)
Abstract : The world is in transition to mobile computing from desktop pc and laptops. There are almost six billion users around the globe. The mobile phones around us are the combination of hardware and the software. There are different Mobile OS as android OS, iOS and windows. Android OS is an open source operating system used in android mobiles. Android is popular in technology companies that require a ready-made, low cost and customizable operating system for high-tech devices. There are various versions from cupcake (April 27, 2009) to Oreo (August 2017) of android. In this paper features of different android versions are compared on the basis of user experience, processing, security and memory management.
An OS that provides a more efficient use of software and hardware resources of a computer system achieves better performance. For each new version of an OS it is expected to have many new features and better performance than the last one. When Microsoft® released two last versions of the Windows® OS for personal computers, i.e. Windows Vista™ in 2007 and afterwards Windows 7™ in 2009, a significant amount of attention was given to their new features, as described in [Bott et al. 09, Hassel et al. 07]. However, performance evaluation and comparison to their predecessors were not conducted in the literature. Although one of the most important design goals for Windows Vista, besides new features and security, was the performance improvement, after it was released most complaints addressed its performance. One of the main reasons was that average computer systems were not powerful enough to take advantages of all Windows Vista features. In contrast to the aforementioned, upon its release, the performance improvement was the most frequently mentioned and praised characteristic of Windows 7. Meanwhile, eternal question appeared among users: “Which Windows OS for personal computers has the best performance?” Furthermore, various comparisons of different versions of the Windows OS for personal computers have emerged on the Internet [see Schmid 07, Smith 09a, Smith 09b, Williams 09]. However, from these performance measurements and comparisons a representative conclusion cannot be drawn since they do not have clear and unified performance measurement process and evaluation methodology. Furthermore, in the literature there are only a few scientific studies on the Windows OS performance, its evaluation and comparison with different versions of the Windows OS for personal computers. Consequently, there is no unified or standard method, process or approach for the Windows OS performance measurement and evaluation. Therefore, the main motivation in this paper is to develop a model for the Windows OSs performance measurement, evaluation and comparison that will be unified and that can be reused. Furthermore, the goal is to use this model for the performance evaluation of the last three versions of the Windows OSs for personal computers.
90 suggest that the Next Generation TCP/IP stack does not bring better throughput in Windows Vista. Symantec researchers Newsham and Hoagland (2006) point out that
“despite the claims of Microsoft developers, the Windows Vista network stack as it exists today is less stable than the earlier Windows XP stack. And a networking stack is a complex piece of software that takes many years to mature.” Therefore, from the results of experiment, the Windows XP operating system shows better network performance than Windows Vista as Windows Vista adopts less stable network stack. The results of experiment present that newer operating system Windows 7 Beta offers better network performance than Windows Vista as it has more matured network stack. In online gaming, Francia (2007) points out that “an extensive test of Battlefield 2, FEAR, and World of Warcraft on both Windows XP and Windows Vista has revealed that gaming performance is far better in Windows XP than in Vista, according to Bigfoot Networks. The results also showed that Vista’s networking stack not only didn’t improve online game play, it often introduced more lag than its predecessor, Windows XP.” That is the same results of the experiment.