Delivery Server Research Articles

An Optimization of Home Delivery Services in a Stochastic Modeling with Self and Compulsory Vacation Interruption

This study presents and discusses the home delivery services in stochastic queuing-inventory modeling (SQIM). This system consists of two servers: one server manages the inventory sales processes, and the other server provides home delivery services at the doorstep of customers. Based on the Bernoulli schedule, a customer served by the first server may opt for a home delivery service. If any customer chooses the home delivery option, he hands over the purchased item for home delivery and leaves the system immediately. Otherwise, he carries the purchased item and leaves the system. When the delivery server returns to the system after the last home delivery service and finds that there are no items available for delivery, he goes on vacation. Such a vacation of a delivery server is to be interrupted compulsorily or voluntarily, according to the prefixed threshold level. The replenishment process is executed due to the (s,Q) reordering policy. The unique solution of the stationary probability vector to the finite generator matrix is found using recursive substitution and the normalizing condition. The necessary and sufficient system performance measures and the expected total cost of the system are computed. The optimal expected total cost is obtained numerically for all the parameters and shown graphically. The influence of parameters on the expected number of items that need to be delivered, the probability that the delivery server is busy, and the expected rate at which the delivery server’s self and compulsory vacation interruptions are also discussed.

Application of Queuing Theory to a Bank’s Automated Teller Machine (ATM) Service Optimization

Automated teller machine (ATM) is one of the several electronic banking channels used in the banking industry. This brought about queue (waiting line) and this is because customers waiting in line to receive service by using the ATM are inevitable and hence queue control became an issue This paper applies queuing theory to determine the average time customers spend on queue and actual time of delivery thereby examining the impact of time wasting and cost associated with it. Direct non-participatory observation and questionnaire were engaged to record time measurements and primary data. Performance measure of the system was calculated and the number of servers for optimum service delivery was also analysed. To analyse customers’ satisfaction, questionnaires were administered to ATM customers. Respondents fairly represent the ATM customer population, males and females, old and young and persons from various occupation backgrounds. Responses from above are analyzed as answers to questions, presented on the questionnaire. For each question, we analyzed using incidences and percentage to determine the weight of support for a particular option. Means, variances and standard derivation are computed for questions on tolerable waiting time and average cash withdrawal. It was commended that the case bank increase the number of servers so as to help reduce wait time and wait cost. From the analysis and observation, service unavailability was observed to be a contributory factor to queue formation at the case ATM.

Detection of Delivery Servers in Online Video Service using Long Short Term Memory Network

Nowadays large scale video delivery networks have been widely deployed. Information about video delivery servers is crucial for a series of network management tasks. However, it is a challenge to identify the delivery servers in the ever-changing content delivery networks. Moreover, it is difficult to find general and flexible features to identify video delivery servers from various video service providers. In this paper, we mainly come up with a novel method based on LSTM (Long Short Term Memory Network) to detect video delivery servers. Experimental results prove that our approach works pretty well by comparing it with the other two conventional machine learning methods. What’s more, our approach can work more flexibly without cumbersome feature extraction relative to conventional machine learning methods.

Technical note: Harmonising metocean model data via standard web services within small research groups

Abstract. Work over the last decade has resulted in standardised web services and tools that can significantly improve the efficiency and effectiveness of working with meteorological and ocean model data. While many operational modelling centres have enabled query and access to data via common web services, most small research groups have not. The penetration of this approach into the research community, where IT resources are limited, can be dramatically improved by (1) making it simple for providers to enable web service access to existing output files; (2) using free technologies that are easy to deploy and configure; and (3) providing standardised, service-based tools that work in existing research environments. We present a simple, local brokering approach that lets modellers continue to use their existing files and tools, while serving virtual data sets that can be used with standardised tools. The goal of this paper is to convince modellers that a standardised framework is not only useful but can be implemented with modest effort using free software components. We use NetCDF Markup language for data aggregation and standardisation, the THREDDS Data Server for data delivery, pycsw for data search, NCTOOLBOX (MATLAB®) and Iris (Python) for data access, and Open Geospatial Consortium Web Map Service for data preview. We illustrate the effectiveness of this approach with two use cases involving small research modelling groups at NATO and USGS.

An Energy-Efficient Strategy for VoD Content Replication in Integrated Metro/Access Networks

The Video-on-Demand (VoD) service is becoming one the most popular Internet services. Due to its bandwidth-consuming nature and thanks to the efforts made by telecom operators to provide the users with higher access rates, an huge amount of VoD traffic is expected to flood the core segment of the network, potentially leading to congestion and Quality of Experience degradation issues. A growing body of research is studying how to alleviate such traffic explosion. One of the most promising solutions consists in migrating the content in the metro and access segments of the network by deploying a system of Metro Servers (MSes) for VoD delivery. This way, the VoD traffic is kept as local as possible and the core network is traffic-offloaded. This paper investigates one of the most prominent risks by adopting this solution: in fact, if not carefully managed, a massive deployment of MSes in the network can lead to a significant increase of the overall energy consumption of the network. We first identify a consistent power model for the MSes and the network equipment in an integrated metro/access architecture scenario, then we define a strategy to switch on and off the network interfaces and the MSes depending on the VoD traffic load variation during the day. We show by means of simulations how our strategy always strikes the best trade-off between the energy consumption for content transport through the network and the energy consumption for processing and storage in the MSes.

Performance evaluation of video server replication in metro/access networks

Internet traffic is increasingly becoming a media-streaming traffic. Especially, Video-on-Demand (VoD) services are pushing the demand for broadband connectivity to the Internet, and optical fiber technology is being deployed in the access network to keep up with such increasing demand. To provide a more scalable network architecture for video delivery, network operators are currently considering novel metro/access network architectures which can accommodate replicated video servers directly in their infrastructure. When servers for VoD delivery are placed nearer to the end users, part of the traffic can be offloaded from the core segment of the network, and the end users can experience better Quality of Service (QoS). While the deployment of caching systems for traffic offloading has been studied in the core network, no work has already investigated the potential performance gains by replicating the content in the metro/access segment of the network, even closer to the users. In our work, we will compare the performance of video server replication in different metro/access network architectures, i.e. a metro ring architecture and a tree-based architecture, by considering both active and passive technologies. We will evaluate using both simulative and analytical methodologies how content providers could benefit from the deployment of replicas of video servers in terms of blocking probability of the VoD requests.

Video quality vs. mobile data billing plans

Despite extensive research regarding the user willingness to pay under different billing plans and prices it is still unclear how users choose a preferred video quality under existing mobile data plans. This is especially important as the usage of adaptive video delivery servers that make use of different video quality levels is increasing. This study presents the results of assessing user preferences for video quality under three different mobile data billing plans. The results show that the user choice of different quality of video content depends on the billing plans used. It also shows that in the case when the mobile data plan is capped but the user has the possibility to pay extra for the exceeding quantity, s/he will choose higher video quality compared to the same plan in which the bandwidth is throttled when the bandwidth is exceeded. No correlation was found between the user choices and age or gender.

Control of Multiple Remote Servers for Quality-Fair Delivery of Multimedia Contents

This paper proposes a control scheme for the quality-fair delivery of several encoded video streams to mobile users sharing a common wireless resource. Video quality fairness, as well as similar delivery delays are targeted among streams. The proposed controller is implemented within some aggregator located near the bottleneck of the network. The transmission rate among streams is adapted based on the quality of the already encoded and buffered packets in the aggregator. Encoding rate targets are evaluated by the aggregator and fed back to each remote video server (fully centralized solution), or directly evaluated by each server in a distributed way (partially distributed solution). Each encoding rate target is adjusted for each stream independently based on the corresponding buffer level or buffering delay in the aggregator. Communication delays between the servers and the aggregator are taken into account. The transmission and encoding rate control problems are studied with a control-theoretic perspective. The system is described with a multi-input multi-output model. Proportional Integral (PI) controllers are used to adjust the video quality and control the aggregator buffer levels. The system equilibrium and stability properties are studied. This provides guidelines for choosing the parameters of the PI controllers. Experimental results show the convergence of the proposed control system and demonstrate the improvement in video quality fairness compared to a classical transmission rate fair streaming solution and to a utility max-min fair approach.

A LICENSE MANAGEMENT SYSTEM FOR CONTENT SEPARATE DELIVERY OVER P2P NETWORK

We propose a license management system for content separate delivery over P2P network. In trivial content delivery systems, a content file is delivered to a user bound license data within content-key simultaneously. However, a server needs to administer not only user license but also content files, and so server's load is heavy in these systems. In our proposed system, users can obtain a content file not only a content delivery server but also other and can be licensed for the content-key separated content delivery. Therefore, our proposed system is lightweight and scalable. Furthermore, for the purpose to show the feasibility, we have implemented a prototype system. As the result of the evaluation, we show our proposed system is secure and practical.

Factors associated with obstetric fistulae occurrence among patients attending selected hospitals in Kenya, 2010: a case control study

BackgroundIn Kenya, about 3000 fistula cases are estimated to occur every year with an incidence of 1/1000 women. This study sought to identify risk factors associated with developing obstetrics fistula in order to guide implementation of appropriate interventions.MethodsAn unmatched case control study was conducted in three major hospitals in Kenya between October and December 2010. Cases were patients who had fistula following delivery within the previous five years. Controls were systematically selected from women who attended obstetrics and gynecology clinics at these hospitals, and did not have present or past history of fistula. Odds ratio was used as measure of association with their corresponding 95% confidence interval. Factors with p value of <0.1 were included into forward additive logistic regression model to generate adjusted odds ratios.ResultsSeventy cases and 140 controls were included in the study. Independent risk factors associated with obstetrics fistula included duration of labour of >24 hours (OR = 4.7, 95% CI = 2.4 -9.2), seeking delivery services after 6 hours of labour onset (OR = 6.9, 95% CI = 2.2-21.3), taking more than 2 hours to reach a health facility (OR = 5.7, 95% CI = 2.9 -11.5), having none or primary education (OR = 9.6, 95% CI = 3.3 –27.9) and being referred to another facility for emergency obstetrics services (OR = 8.6, 95% CI = 2.7 –27).ConclusionsRisk factors for developing obstetrics fistula were delays in care seeking including delay in making decision to seek delivery servers after six hours of labour onset, taking more than two hours to reach a health facility, labour duration of more than 24 hours and having no formal or primary education. Efforts geared at strengthening all levels of the health system to reduce delays in access to emergency obstetric care are needed.

Utilizing the IP Multimedia Subsystem to create an extensible service-oriented architecture

Smart Spaces provide very promising means of creating context-aware environments. Unfortunately, a lack of information about users within Smart Spaces limits their usefulness. We propose a novel solution that involves integrating Smart Spaces with social networks through the IP Multimedia Subsystem. to create truly context-aware and adaptive spaces. By utilizing the wealth of user information present within social networks, smarter and more adaptive spaces can be created. We therefore propose the design and implementation of “SocioSpace” a Smart Spaces framework that utilizes the social context. We design and implement all components of SocioSpace, including the central server, the location management system, social network interfacing components, service delivery server and user agents. We then run various scenarios to test the reliability of the system. The results show the effectiveness of our framework in successfully creating Smart Spaces that can truly utilize social networks to deliver adaptive services that enhance the users’ experiences and make the environment more beneficial to them.

A Portable Method to Improve the Performance of Commodity Servers for Massive Data Delivery

With the progress of a Multi Core technique, the number of processes, which are executed concurrently on the server, has been increasing. Accordingly, the amounts of data transmitted by the servers, which deliver a large amount of data to many clients like VOD servers, also have been increasing dramatically. However, the powerful interconnection networks (Myrinet [1], Infiniband [2], etc.) are expensive without exception. Then this paper proposes the low-cost (low-priced and easy-work) method to improve the bandwidth performance. The method achieves it by bringing out the hardware performance of multiple GbE ports installed on the server. Due to advents of low-priced Multi GbE Ports Card and PCI Express slots, it is easy to install multiple GbE ports to the server. In addition, the method offers equal service (bandwidth) to all clients.

遠隔地施設への３Ｄ医用画像配信の検討

Using a 3D-imaging-create-function server and network services by IP-VPN, we began to deliver 3D images to the remote institution. An indication trial of the primary image, a rotary trial of a 3D image, and a reproducibility trial were studied in order to examine the practicality of using the system in a real network between Hakodate and Sapporo (communication distance of about 150 km). In these trials, basic data (time and receiving data volume) were measured for every variation of QF (quality factor) or monitor resolution. Analyzing the results of the system using a 3D image delivery server of our hospital with variations in the setting of QF and monitor resolutions, we concluded that this system has practicality in the remote interpretation-of-radiogram work, even if the access point of the region has a line speed of 6 Mbps.

Dynamic file grouping for load balancing in streaming media clustered server systems

A dynamic file grouping strategy is presented to address the load balancing problem in streaming media clustered server systems. This strategy increases the server cluster availability by balancing the workloads among the servers within a cluster. Additionally, it improves the access hit ratio of cached files in delivery servers to alleviate the limitation of I/O bandwidth of storage node. First, the load balancing problem is formulated as a two layers semi-Markov switching state-space control process. This analytic model captures the behaviors of streaming media clustered server systems accurately, and is with constructional flexibility and scalability. Then, a policy iteration based reinforcement learning algorithm is proposed to optimize the file grouping policy online. By utilizing the features of the event-driven policy, the proposed optimization algorithm is adaptive and with less computational cost. Simulation results demonstrate the effectiveness of the proposed approach.

Structuring connections between content delivery servers groups

Content Delivery Servers can be grouped into logical networks according to several criteria: similar characteristics; functionalities; type of data delivered or proximity. Sometimes, it could be useful to find a way to join these autonomous logical networks. Research in this area focuses in centralized solutions, e.g. using a single point for data delivery between these groups. This paper proposes a novel architecture to interconnect content delivery servers from different groups and explains how they establish logical connections. The topology of logical connections, between servers clustered in different groups, changes depending on their capacity or because of server failures. The proposal is based on a hierarchical structure, in which the role of the server in the architecture is given by several parameters, being also scalable and fault-tolerant. We present the analytical model for this interconnection architecture and results obtained for some defined parameters. Finally, developed an application which used the protocol described in this paper and we deployed the proposed architecture in a real environment to obtain accurate measurements.

The life cycle of multimedia metadata

During its lifetime, multimedia content undergoes different stages or cycles from production to consumption. Content is created, processed or modified in a postproduction stage, delivered to users, and finally, consumed. Metadata, or descriptive data about the multimedia content, pass through similar stages but with different time lines. Metadata may be produced, modified, and consumed by all actors involved in the content production-consumption chain. At each step of the chain, different kinds of metadata may be produced by highly different methods and of substantially different semantic value. Different metadata let us tie the different multimedia processes in a life cycle together. However, to employ these metadata, they must be appropriately generated. The CODAC Project, led by Harald Kosch, implements different multimedia processes and ties them together in the life cycle. CODAC uses distributed systems to implement multimedia processes. The project's core component is a multimedia database management system (MMDBMS) which stores content and MPEG-7-based metadata. It communicates with a streaming server for data delivery. The database is realized in the multimedia data cartridge (MDC) - which is an extension of the Oracle database management system - to handle multimedia content and MPEG-7 metadata.

A content delivery infrastructure to support advanced services for business travellers

A content delivery network (CDN) is a collection of network elements and procedures designed to efficiently connect information consumers with information providers, accelerating end-users access to contents and reducing network traffic and hardware requirements. The advent of nomadic users implies that CDNs should deal with routing and forwarding of requests for contents in a mobile environment too. The scenario we consider in this paper is that of the IST FIFTH project, where a local network on board a fast train is connected either via a satellite link or a Wireless-LAN access to the fixed content network. In this framework, we define a hierarchical structure of content servers for data management and delivery to business travellers on board trains. In addition, we propose a users' request routing approach to perform smart server selection, taking into account both network and server congestion.

Regionalization of extreme precipitation estimates for the Alabama rainfall atlas

The Alabama Rainfall Atlas is an internet-based server for delivery of design information on the characteristics of extreme precipitation throughout the state. Products delivered include intensity-duration-frequency (IDF) curves and 24-h design storm hyetographs based on US Soil Conservation Service (now the Natural Resources Conservation Service) methods. Three databases (daily, hourly, subhourly) upon which the server relies consist of at-site estimates of generalized extreme value distribution parameters for gauging sites throughout the state. Regionalization of those at-site estimates to develop precipitation products for a user-specified location is accomplished using a hybrid estimation method that consists of a weighted average of estimators based on gauging station proximities and record lengths. The regionalization procedure provides products on demand for any user-selected location (gauged or ungauged) and does not cause discontinuities at boundaries that would result from delineation of distinct regions. The databases are compact and user-requested products are produced and delivered nearly instantaneously. These latter issues are felt to be major ones considering the internet-based delivery method.

분산 이벤트 서비스를 이용한 이동 에이전트 추적

본 논문은 이동 에이전트를 추적하는 기존 메커니즘들을 심층 분석하여 문제점을 도출하였고, 이러한 문제점을 해결한 분산 이벤트 서비스 기반 에이전트 추적 모델을 제안하였으며, 이를 적용한 에이전트 감시 시스템을 구현하여 제안한 추적 모델의 성능을 분석하였다. 안한 에이전트 추적 모델은 에이전트 이동이 발생하여도 에이전트 추적이 항상 가능하며, 다중 클라이언트가 동시에 한 에이전트를 추적할 수도 있게 한다. 그리고 에이전트가 이동할 때마다 이를 추적하는 모든 클라이언트에게 위치를 알려주어 클라이언트가 항상 정확하게 에이전트 위치를 파악할 수 있게 하는 위치추적 유형과 메시지를 전달하는 통로를 항상 신뢰할 수 있는 상태로 설정하는 경로설정 유형을 모두 지원한다. In this paper, we analyzed the known agent tracking models and proposed a new agent tracking model based on the distributed event service that always assures reliable tracking. Also we experimented the Performance of the event servers on the agent monitoring system that implements the distributed event service and showed their performance to decrement gracefully. The proposed tracking model doesn't make only several clients trace a mobile agent which moves among agent servers autonomously, but also supports two types of agent tracking agent location tracking that notifies agent location to the clients and path establishment that maintains reliable connection between agent servers for message delivery.

The HotMedia architecture: progressive and interactive rich media for the Internet

HotMedia is a novel scalable solution for delivering interactive rich media over the Internet. It is a delivery-suitable file format that can contain heterogeneous compositions of media bit streams as well as meta-data that define the behavior, composition, and interaction semantics. This enables the creation of lightweight single-file representations of interactive, multiphase presentations involving multiple media-type content. The HotMedia client has a smart content algorithm that infers types from the incoming data stream and fetches the media renderer components, user-interface components, and hyper-linked action components, all just-in-time, resulting in progressive and contest driven enrichment of the user experience. Internet users get a simple initial experience with minimal latency followed by enrichment of this experience. HotMedia has an open and extensible architecture, which enables and encourages the inclusion of new media-types, user-interfaces, and hyper-linked actions. By separating media-rendering from action-performing, it lets all media handle the same actions. HotMedia can also track on the server-side, user interactions and user-experience associated parameters. In its simplest usage HotMedia requires no more than a regular web server for delivery and no client-side preinstallation.