Analyzing Service Rates for File Transfers in Peer-to-peer File Sharing Systems

When examining the file transfer performance in a peer-to-peer file sharing system, a fundamental problem is how to describe the service rate for a file transfer. In this paper, the problem is examined by analyzing the distribution of server-like nodes' upstream-bandwidth among their concurrent transfers. A sufficient condition for the service rate, what a receiver obtains for downloading a file, to asymptotically be uniform is presented. On the aggregate service rate for transferring a file in a system, a sufficient condition for it to asymptotically follow a Zipf distribution is presented. These asymptotic equalities are both in the mean square sense. These analyses and the sufficient conditions provide a mathematic base for modeling file transfer processes in peer-to-peer file sharing systems.

Comprehensive Utility Function for Resource Allocation in Mobile Edge Computing

In mobile edge computing(MEC),one of the important challenges is how much resources of which mobile edge server(MES)should be allocated to which user equipment(UE).The existing resource allocation schemes only consider CPU as the requested resource and assume utility for MESs as either a random variable or dependent on the requested CPU only.This paper presents a novel comprehensive utility function for resource allocation in MEC.The utility function considers the heterogeneous nature of applications that a UE offloads to MES.The proposed utility function considers all important parameters,including CPU,RAM,hard disk space,required time,and distance,to calculate a more realistic utility value for MESs.Moreover,we improve upon some general algorithms,used for resource allocation in MEC and cloud computing,by considering our proposed utility function.We name the improved versions of these resource allocation schemes as comprehensive resource allocation schemes.The UE requests are modeled to represent the amount of resources requested by the UE as well as the time for which the UE has requested these resources.The utility function depends upon the UE requests and the distance between UEs and MES,and serves as a realistic means of comparison between different types of UE requests.Choosing(or selecting)an optimal MES with the optimal amount of resources to be allocated to each UE request is a challenging task.We show that MES resource allocation is sub-optimal if CPU is the only resource considered.By taking into account the other resources,i.e.,RAM,disk space,request time,and distance in the utility function,we demonstrate improvement in the resource allocation algorithms in terms of service rate,utility,and MES energy consumption.

Analysis of Incremental Load Damaging Effects of Overloaded Trucks on Federal Highway Pavement Structures in Nigeria

The study is to assess the present serviceability rating of Nigerian highways and the load damage effects of overloaded trucks. The researchers used the American Association of State Highway and Transportation Officials (AASHTO) methods. In this study, the highway section of Lokoja-Abuja, Ilorin-Jebba and Abakiliki-Ogoja via Mbok roads were selected, and data were collected through an axle-load survey, automatic traffic count and from secondary sources. The rate of gross vehicle weight violation was found, ranging from 20% to 94% of the axle load distribution across the studied network. Comparing the overloaded vehicle damage factor (V.D.F.) and standard V.D.F., the range was from 1.2 to 41.34 times across the road networks studied, and this explained why the pavement structures of Nigerian roads tend to deteriorate during its service life rapidly. Present serviceability rating was estimated at 3.45, 4.41 and 3.35 for Lokoja-Abuja, Ilorin-Jebba and Abakiliki-Ogoja roads respectively, showing depletion from their initial conditions. The damaging effects of the HGV are less severe at Lokoja-Abuja Road (with g = 0.30), followed by Ilorin-Jebba Road (with g = 0.35) and more in Abakiliki-Ogoja Road (with g = 0.43). The heaviest overload of 94% of the 6-axle vehicles plying at the Lokoja-Abuja road could explain this intense damaging effect on the road pavement

Development of a Model for International Traveler’s Check-In Process Using Arena Software Tool

The increasing demand for airline services amidst limited resources results in passenger dissatisfaction and dwindling revenue for airports and airlines. The dynamics of service demand and resource supply results in check-in issues for the stakeholders in the commercial aviation industry. This has the effect of impacting negatively on service performance, cost of operations, customer satisfaction, and overall throughput. Hence, this paper modelled the travelers’ check-in process at the “D Wing” of the Departure Section of Murtala Muhammed International Airport (MMIA), Ikeja, using Arena Software Tool. The work was carried out by determining the parameters of the queues at designated service points in the check-in process. The primary data required to develop the model were acquired by direct observation of passenger flow and oral interview. Thus, the average check-in time was determined. Thereafter, a model of the international check-in system of the MMIA was developed using Arena software in combination with Microsoft Office tools. The data collected were therefore inputted into the model and simulated;the real result was compared with the simulation result of 133 completions and there was no significant difference. The result showed that the model is a representation of the real system under study. Further work will be tailored towards simulation (i.e. the model will be subjected to experimentation in order to have different scenario).

Simulation of a Model for International Traveler’s Check-In Process Using Arena Software Tool

With the current situation of insecurity in Nigeria and the worsening condition of Nigerian roads, there is increasing demand for air travel. This increasing demand for airline services amidst limited resources results in passenger dissatisfaction and reduction of revenue for airports and airlines. The dynamics of service demand and resource supply result in check-in issues for all the stakeholders in the commercial aviation industry. Hence, this research simulated the developed model for travelers’ check-in process at the “D Wing” of the Departure Section of Murtala Muhammed International Airport (MMIA), Ikeja, using Arena Software Tool. The simulation of the developed model was carried out by varying five different configurations of the servers with respect to the baggage weighing machines and passenger profiling devices to obtain the minimum average check-in time (ACT) for the process, with each configuration undergoing 133 completions of simulation runs. The result of the experimentation revealed that the 3 × 3 × 4 configuration of servers produced the smallest ACT of 18.25 minutes. This translates to a difference of about 58 minutes from the 76.16 minutes ACT of the real system;representing about 76% improvement in the check-in time of passengers. This study contributed to knowledge by revealing that the main choke points in the MMIA check-in system occur at the baggage weighing and passenger profiling areas as against the check-in counter sub-section as advanced by previous works. Furthermore, the research added value to knowledge by creating a balance between customer satisfaction and cost of operations thereby accommodating the interests of the passenger and the operator who are the two main stakeholders in the commercial aviation industry.

Performance Analysis of a Discrete-Time Queue with Working Breakdowns and Searching for the Optimum Service Rate in Working Breakdown Period

This paper deals with a discrete-time Geo/Geo/1 queueing system with working breakdowns in which customers arrive at the system in variable input rates according to the states of the server. The server may be subject to breakdowns at random when it is in operation. As soon as the server fails, a repair process immediately begins. During the repair period, the defective server still provides service for the waiting customers at a lower service rate rather than completely stopping service.We analyze the stability condition for the considered system. Using the probability generating function technique, we obtain the probability generating function of the steady-state queue size distribution.Also, various important performance measures are derived explicitly. Furthermore, some numerical results are provided to carry out the sensitivity analysis so as to illustrate the effect of different parameters on the system performance measures. Finally, an operating cost function is formulated to model a computer system and the parabolic method is employed to numerically find the optimum service rate in working breakdown period.

The Queuing Model of M/M/S/K ＋ M Based on the Impatience and Changeable Service Rate

The work flow of call center is a typical stochastic service system. This article exploites service rate, which is the most controllable artificial factor of call center, and integrates the abandoning rate of impatient customers, models a new-style call center＇s queuing model - the queuing model of M/M/S/K ＋ M based on the impatience and changeable service rate. Then, making use of the traffic forecast result coming from the time series, it models to figure out the numbers of agents per hour, and complete the agents＇ office-hour arrangements in the restriction of some system indexes. Finally, it optimizes the design method by the contrast and analysis of the changeable service rate model and the traditional regular service rate model.