Decrease In Throughput Research Articles

Urban road congestion, capacity expansion and port competition: empirical analysis of US container ports

In this study, we empirically investigate the impacts of urban road congestion and road capacity expansion on the competition between major container ports in the US. We find that more delays on urban roads may cause shippers to switch to competing rival ports: a 1% increase in road congestion delays around the port is associated with a 0.90–2.48% decrease in the port's container throughput but a 0.62–1.69% increase in the rival port's throughput. Adding local roads tends to benefit the port and harm its rival (in terms of throughput) by reducing road congestion. However, the overall impact of road provision on ports’ throughput varies among the sample ports, as road capacity expansion may affect ports’ output through channels other than road congestion delays.

PERFORMANCE EVALUATION OF MODIFIED AODV AGAINST BLACK HOLE ATTACK IN MANET

A mobile ad-hoc network is an infrastructure less network which consists of a number of mobile nodes that dynamically form a temporary network for the transmission of data from source to destination. They are composed of nodes that relay on each other to manage and for secure transmission of traffic due to lack of centralized administration. As MANETs become widely used, the security issue has become one of the primary concerns for all the times. One of the well known attack is the Black Hole attack which is most common in the on-demand routing protocols such as AODV. In this paper, the proposed solution is to modify the AODV routing protocol in such a way that it can combat the cooperative Black Hole attack. The results show an effective increase in throughput and PDR and decrease in average end-to-end delay with a slight increase in routing overhead.

Energy Supported AODV (EN-AODV) for QoS Routing in MANET

A Mobile Ad-hoc Network (MANET) is a wireless network competent of autonomous actions. No infrastructure is required for nodes to communicate with each other in the network. MANET operates without centralized administration. The nodes are self configuring, independent, quickly deployable. Nodes are movable since topology is very vibrant and they have restricted energy and computing resources. Routing protocols should incorporate QoS metrics in route finding and maintenance, to support end-to-end QoS. General AODV routing faces problems like long route, time delay, mobility and many other while routing. The nodes low in energy level will not be in a position to complete the routing. The QoS parameters like throughput, PDR and delay are affected directly. The proposed Energy based AODV protocol (EN-AODV) announces energy and based on nodes sending and receiving rates and the sizes of the data to be transmitted it justifies whether its energy level is maintained or decreased. It calculates the energy levels of the nodes before they are selected for routing path. A threshold value is defined and nodes are considered for routing only if its energy level is above this threshold value. The work is implemented and simulated on NS-2. The simulation results have shown an increase in PDR, decrease in delay and throughput is maintained. The proposed EN-AODV provides more consistent and reliable data transfer compared to general AODV.

Towards a context sensitive and secure routing for in MANETs (Mobile Ad-hoc Networks)

Mobile Ad-hoc Networks (MANETs) can be deployed quickly without any existing infrastructure. These networks are useful in many areas, such as emergency assistance, disaster relief, intelligent systems houses, patient monitoring, industrial applications, health monitoring, environmental control, military applications, etc. However ad-hoc networks face many challenges, such as the unpredictable mobility of the network, the limited amount of energy available, security challenges, low computational resources, low memory, etc. There is a need for routing approaches aware of those challenges. Thus, this work aims to provide a secure and context aware ad-hoc network, by changing the frequency of data transmission and routing the packets through reliable links. The proposed approaches has been tested, the results shows an interesting decrease of the transmission throughput coming from malicious nodes, a decrease in the packet loss and an increase of the network lifetime.

Revisiting the Cycle Length

During oversaturation, a popular objective in traffic signal operations is to maximize throughput to keep traffic moving. As cycle lengths are increased, the proportion of lost time used to transition between signal phases is reduced. This factor is often a rationale for programming long cycle lengths into signal timing plans. An investigation of the impact of cycle length revisited the concept of the use of critical lane analysis to calculate throughput and applied the technique to data collected at an oversaturated intersection in Indianapolis, Indiana. Traffic volumes were measured for 10 weeks while various cycle lengths, ranging from 80 to 135 s, were tested at the intersection. During saturated conditions, no clear increase in the sum of critical lane throughput was observed, even when the cycle length increased by more than 50%. At 135 s, there was a slight reduction in the total critical lane sum volume. These findings concur with a recent study by Denney et al. The decrease in throughput during the longer cycle lengths is attributed to the reduction of saturation flow during long green times. Possible results of use of a time-dependent saturation flow rate are discussed. Additionally, critical lane analysis may have applications to evaluation and ranking of intersections within corridors as under, near, or over saturation.

A New Simulation Architecture for Communication Network Systems with Application to HF Radio

 Abstract—This paper describes a simulation architecture developed to address the need in the defence and aerospace industry for a rapid prototyping capability to test new and existing network protocols and systems where analytical methods no longer suffice. In particular, the simulator introduced here allows study of High Frequency (HF) radio networks and other unorthodox systems that cannot be easily modelled using existing communications network simulators. This paper describes the architecture and gives an example use case - modelling an HF System using the 2G Automatic Link Establishment (ALE) linking protocol under a variety of conditions; exploring the effects of changing the number of nodes in the network, and of altering the input data rate to the system. The network performance was analysed under a wide range of combinations of conditions, and it was found that increasing the number of nodes in these networks causes specific latency increases and an overall throughput decrease, both in the unidirectional and bidirectional case, although it is better tolerated in the unidirectional case. Increasing the input data rate causes an overall throughput increase up to a threshold point, after which it saturates and then decreases as data remains unsent, due to the physical limits of the system (including networking overhead) being surpassed. This simulator, known as CommNetSim has been developed for use in evaluating the technical capabilities of, and business cases for, real-world applications to be developed by Thales UK. Index Terms—Communication networks, discrete event simulation, high frequency radio, modelling, simulation.

No-Notice Evacuation Management

To promote smoother freeway traffic flow during evacuations, ramps may be closed and thus reduce the number of merging and related speed reduction points. Deciding which ramps to close can be treated as an optimization problem in which the decision variables are integers that indicate whether the ramp is open or closed. This paper examines the problem under multiple demand and budget scenarios for no-notice evacuations. Through the optimization formulation and solution method, optimized closure plans are developed for each scenario and compared with the do-nothing case, and an existing plan is developed with professional judgment. The optimized plans outperform the others in the evacuees' total travel time but are sometimes associated with decreases in overall network throughput. Three ramp closures, consistent across the scenarios, are explored as a reduced closure plan, and evacuee benefits are identified for all of the scenarios over the do-nothing option except in the most congested background traffic scenario. However, even in the most congested case, the three-ramp closure plan improved evacuees' travel times over the plan developed without analytical and simulation support. Although the exact optimized ramp closure plan varies across scenarios and budgets, overlap of the plans can help generate a smaller closure plan that provides benefits over plans that are strictly judgment based and over the do-nothing option in less congested cases.

Investigation of Storage Options for Scientific Computing on Grid and Cloud Facilities

In recent years, several new storage technologies, such as Lustre, Hadoop, OrangeFS, and BlueArc, have emerged. While several groups have run benchmarks to characterize them under a variety of configurations, more work is needed to evaluate these technologies for the use cases of scientific computing on Grid clusters and Cloud facilities. This paper discusses our evaluation of the technologies as deployed on a test bed at FermiCloud, one of the Fermilab infrastructure-as-a-service Cloud facilities. The test bed consists of 4 server-class nodes with 40 TB of disk space and up to 50 virtual machine clients, some running on the storage server nodes themselves. With this configuration, the evaluation compares the performance of some of these technologies when deployed on virtual machines and on “bare metal” nodes. In addition to running standard benchmarks such as IOZone to check the sanity of our installation, we have run I/O intensive tests using physics-analysis applications. This paper presents how the storage solutions perform in a variety of realistic use cases of scientific computing. One interesting difference among the storage systems tested is found in a decrease in total read throughput with increasing number of client processes, which occurs in some implementations but not others.

Wi-Fi 네트워크간의 신호간섭 및 데이터 전송률 영향 분석

최근 스마트폰과 같은 무선통신기기의 급증으로 인하여 IEEE 802.11 Wi-Fi 네트워크에서 인접 네트워크간의 신호간섭현상이 많이 발생하며, 이와 같은 신호간섭현상은 데이터 전송 품질에도 영향을 미친다. 현재 출시되고 있는 다수의 Wi-Fi 관련 제품들은 높은 데이터 전송률 및 넓은 전송범위를 보여주고 있지만, 반면 이 같은 특성은 인접한 무선기기와의 무선신호간섭 확률도 높게 한다. 무선신호간섭은 무선통신 특성상 피하기 어려운 현상이지만 통신기기의 신호전송범위를 작게 함으로서 최소화할 수 있다. 그러나 작은 신호전송범위는 낮은 송신강도를 의미하므로, 이는 낮은 데이터 전송률로 나타나게 된다. 이에 본 논문에서는 신호강도, 전송률, 신호간섭간의 상호 관계를 분석하고, 이러한 관계로부터 데이터 전송률에 미치는 영향을 실험과 시뮬레이션을 통하여 구한다.

QoS routing in wireless sensor networks—a survey

A wireless sensor network (WSN) is a one made up of small sensing devices equipped with processors, memory, and short-range wireless communication. Sensor nodes, are autonomous nodes, which include smart dust sensors, motes and so on. They co-operatively monitor physical or environmental conditions and send the sensed data to the sink node. They differ from traditional computer networks due to resource constraints, unbalanced mixture traffic, data redundancy, network dynamics, and energy balance. These kinds of networks support a wide range of applications that have strong requirements to reduce end-to-end delay and losses during data transmissions. When large numbers of sensors are deployed in a sensor field and are active in transmitting the data, there is a possibility of congestion. Congestion may occur due to buffer overflow, channel contention, packet collision, a high data rate, many to one nature, and so on. This leads to packet loss which causes a decrease in throughput and lifetime. Maximum throughput, energy efficiency and minimum error rate can be achieved by minimizing the congestion. A number of quality of service (QoS) techniques has been developed to improve the quality of the network. This article gives an overview of existing QoS techniques and a parametric comparison made with recent developments. This article mainly concentrates on network congestion in WSN environment.

Comparison of in-gel protein separation techniques commonly used for fractionation in mass spectrometry-based proteomic profiling.

Fractionation of complex samples at the cellular, subcellular, protein, or peptide level is an indispensable strategy to improve the sensitivity in mass spectrometry-based proteomic profiling. This study revisits, evaluates, and compares the most common gel-based protein separation techniques i.e. 1D SDS-PAGE, 1D preparative SDS-PAGE, IEF-IPG, and 2D-PAGE in their performance as fractionation approaches in nano LC-ESI-MS/MS analysis of a mixture of protein standards and mitochondrial extracts isolated from rat liver. This work demonstrates that all the above techniques provide complementary protein identification results, but 1D SDS-PAGE and IEF-IPG had the highest number of identifications. The IEF-IPG technique resulted in the highest average number of detected peptides per protein. The 2D-PAGE was evaluated as a protein fractionation approach. This work shows that the recovery of proteins and resulting proteolytic digests is highly dependent on the total volume of the gel matrix. The performed comparison of the fractionation techniques demonstrates the potential of a combination of orthogonal 1D SDS-PAGE and IEF-IPG for the improved sensitivity of profiling without significant decrease in throughput.

FFR 기반의 Femtocell 네트워크를 위한 적응 주파수 자원 할당 방법

According to distribute of resource of macro cell and reduce distance between transmitter and receiver, Femto cell system is promising to provide costeffective strategy for high data traffic and high spectral efficient services in future wireless cellular system environment. However, the co-channel operation with existing Macro networks occurs some severe interference between Macro and Femto cells. Hence, the interference cancellation or management schemes are imperative between Macro and Femto cells in order to avoid the decrease of total cell throughput. First, we briefly investigate the conventional resource allocation and interference cancellation scheme between Macro and Femto cells. So we found that cell throughput and frequency reuse ware decreased Then, we propose an adaptive resource allocation scheme based on the distribution of Femtocell traffic in order to increase the cell throughput and also maximize the spectral efficiency over the FFR (Fractional Frequency Reuse) based conventional resource allocation schemes. Simulation Results show that the proposed scheme attains a bit similar SINR (Signal to Interference Noise Ratio) distribution but achieves much higher total cell throughput performance distribution over the conventional resource allocation schemes for FFR and future IEEE 802.16m based Femtocell network environment.

An Energy Efficient Congestion control Technique for Wireless Sensor Networks

WSN are distributed networks with small, light weight wireless sensor nodes. These sensor nodes cooperatively monitor the environment to measure the physical parameter such as temperature, pressure etc. It is data centric. When sensor nodes detect an event, it become active in collecting and transmitting the data, which cause congestion and results in packet drops, decrease in throughput and retransmission of data. To ensure the application’s reliability requirements and to reduce the load on the network, WSN need proficient congestion control policies. With this aim, this paper evaluates a contextual cooperative congestion control policy that makes use of the environment information of each node to reduce the channel load, by satisfying the applications requirements. This paper proposes a selective data forwarding scheme to avoid congestion and to optimize the energy drain. The SDFS scheme depends on parameters such as available energy and precedence of the data at the node. This scheme collects data from other sensors of this context.

AP의 채널 설정 및 밀집도에 따른 무선 랜의 전송 속도에 관한 실험

본 논문에서는 2.4 GHz 대역을 사용하는 802.11 기반의 무선 랜 상호간 전파 간섭에 따른 전송 속도에 관한 실험이다. 최근, 휴대용 노트북과 스마트폰의 활성화로 무선 랜 밀집 공간이 증가함에 따라, 이 공간에서 설치된 무선 랜 간에 전파 간섭으로 인한 전송 속도 저하가 우려되고 있다. 이와 관련하여 본 논문은 다수 무선 랜에 설치된 시나리오를 구성하여 채널 조합에 따른 전송 속도를 측정하여 보다 효율적인 채널 조합을 제시하였고, 설치된 AP의 수에 따른 전송 속도를 측정하여 설치 AP의 수와 전송 속도와의 관계를 도출하였다. 측정 결과, 보다 효율적인 채널 조합으로 1, 5, 9, 13을 제시하며, 설치 AP의 밀집도가 증가할수록 전송 속도는 감소하는 것으로 나타났다. This paper is about the experiment which is throughput of WLANs based on 802.11 due to interference each other. Recently, WLAN has been increased due to generalization of smart-phone and potable notebook. Therefore, the decrease of throughput because of interference between WLANs is expected. In regard of this, the throughput of WLANs according to channelling is measured in order to figure out efficient channelling and the throughput of WLANs according to the number of AP was measured in order to get relation between number of AP and throughput. Then, more efficient channelling of 1, 5, 9, 13 is suggested and the throughput of WLAN is decreased as increasing of number of AP.

인터페이스간 동적 부하 분배를 고려한 다중 인터페이스 액세스 포인트 설계 및 구현

Recently, smartphone, notebook, PC and other supporting wireless LAN device have come into wide use. By increasing user that use wireless LAN device, wireless traffic also increased. If wireless traffic through one AP is increase, it causes throughput decrease. To solve this problem, wireless LAN service provider install more AP where overload occurred. But this is not enough. Because stations can't know AP's load factor, and APs do nothing for load balancing. In this paper, we propose Multi-Interface Access Point(MIAP) to solve this problem. MIAP operate same as multiple APs with multi-interface, and MIAP measure each interface's load periodically. If MIAP detect overloaded interface, MIAP transfer station from overloaded interface to under-loaded interface. We conducted an experiment for verifying existing problem, and we found this problem occurred. We plan an experiment scenario for a comparison between existing AP and MIAP, and excute these experiment. In the result, we show MIAP with load balancing can improve total throughput about 72% and stabilize delay jitter than existing AP.

Systematic Comparison of Fractionation Methods for In-depth Analysis of Plasma Proteomes

Discovery and validation of plasma biomarkers are quite challenging because of the high complexity and wide dynamic range of the plasma proteome. Current plasma protein profiling strategies usually use major protein immunodepletion and nanoLC-MS/MS as the first and final analytical steps, respectively, but additional fractionation is needed to detect and quantify low-abundance disease biomarkers. In this study, the performances of 1-D SDS-PAGE, peptide isoelectrofocusing, and peptide high pH reverse-phase chromatography for fractionation of immunodepleted human plasma were systematically compared by evaluating protein coverage, peptide resolution, and capacity to detect known low-abundance proteins. Trade-offs between increasing the number of fractions to improve proteome coverage and resulting decreases in throughput also were assessed. High pH reverse-phase HPLC exhibited the highest peptide resolution and yielded the best depth of analysis with detection of the largest number of known low-abundance proteins for a given level of fractionation. Another advantage of using high pH reverse-phase fractionation rather than 1-D SDS gels is that all fractionation steps except for abundant protein depletion occur at the peptide level, making this strategy more compatible with quantitative biomarker validation methods such as stable isotope dilution multiple reaction monitoring.

Teaching and Clinical Efficiency: Competing Demands

Introduction: Teaching ability and efficiency of clinical operations are important aspects of physician performance. In order to promote excellence in education and clinical efficiency, it would be important to determine physician qualities that contribute to both. We sought to evaluate the relationship between teaching performance and patient throughput times.Methods: The setting is an urban, academic emergency department with an annual census of 65,000patient visits. Previous analysis of an 18-question emergency medicine faculty survey at this institution identified 5 prevailing domains of faculty instructional performance. The 5 statistically significant domains identified were: Competency and Professionalism, Commitment to Knowledge and Instruction, Inclusion and Interaction, Patient Focus, and Openness and Enthusiasm. We fit a multivariate, random effects model using each of the 5 instructional domains for emergency medicine faculty as independent predictors and throughput time (in minutes) as the continuous outcome. Faculty that were absent for any portion of the research period were excluded as were patient encounters without direct resident involvement.Results: Two of the 5 instructional domains were found to significantly correlate with a change inpatient treatment times within both datasets. The greater a physician’s Commitment to Knowledge and Instruction, the longer their throughput time, with each interval increase on the domain scale associated with a 7.38-minute increase in throughput time (90% confidence interval [CI]: 1.89 to 12.88 minutes). Conversely, increased Openness and Enthusiasm was associated with a 4.45-minute decrease in throughput (90% CI: 8.83 to 0.07 minutes).Conclusion: Some aspects of teaching aptitude are associated with increased throughput times (Openness and Enthusiasm), while others are associated with decreased throughput times (Commitment to Knowledge and Instruction). Our findings suggest that a tradeoff may exist between operational and instructional performance. [West J Emerg Med. 2012;13(2):186–193.]

Effects of ore characteristics on product shape properties and breakage mechanisms in industrial SAG mills

The effect of ore characteristics on the particle shape were studied using two detailed industrial surveys to monitor breakage events taking place inside industrial Semi-Autogenous (SAG) mills as a function of ore hardness. In order to validate the ore hardness effect, the SAG mill was operated in a controlled condition as much as possible. Different methods, including point load index, drop weight test, Bond mill work index and abrasion index, were employed to appropriately characterize the entering feed strength to the circuit. In addition, the shape of SAG mill products was quantified using an image analyzer system, for which elongation and angularity descriptors were calculated.Experimental studies have indicated that an increase in ore hardness is associated with an increase in point load index and Bond work index and a decrease in impact breakage parameter (A×b). Moreover, an increase in ore hardness corresponds to an increase in feed size. Hard ore grinding in the SAG mill resulted in finer products compared to the soft ore milling. In addition, it was found that the products of the soft ore milling were more elongated, angular and less rounded than those of the hard ore milling. This was attributed to changes in breakage mechanisms as ore strength changes. The weaker ore is ground mainly by the impact breakage while the stronger ore is subjected to abrasion and attrition events where the media impact could not sufficiently break the stronger particles. It was also found that the particle angularity and elongation distributions were fitted to the 3-parameter lognormal distribution, providing a convenient way to quantify changes in particle shape properties as a function of the ore characteristics. It was concluded that the main reason underlying the decrease of circuit throughput from 939 to 498t/h was due to changes in breakage mechanisms.

Trust Based Scheme for QoS Assurance in Mobile Ad-Hoc Networks

A mobile ad-hoc network (MANET) is a peer-to-peer wireless network where nodes can communicate with each other without the use of infrastructure such as access points or base stations. These networks are self-configuring, capable of self-directed operation and hastily deployable. Nodes cooperate to provide connectivity, operates without centralized administration. Nodes are itinerant, topology can be very dynamic and nodes must be able to relay traffic since communicating nodes might be out of range. The dynamic nature of MANET makes network open to attacks and unreliability. Routing is always the most significant part for any networks. Each node should not only work for itself, but should be cooperative with other nodes. Node misbehaviour due to selfish or malicious intention could significantly degrade the performance of MANET. The Qos parameters like PDR, throughput and delay are affected directly due to such misbehaving nodes. We focus on trust management framework, which is intended to cope with misbehaviour problem of node and increase the performance of MANETs. A trust-based system can be used to track this misbehaving of nodes, spot them and isolate them from routing and provide reliability. In this paper a Trust Based Reliable AODV [TBRAODV] protocol is presented which implements a trust value for each node. For every node trust value is calculated and based trust value nodes are allowed to participate in routing or else identified to become a misbehaving node. This enhances reliability in AODV routing and results in increase of PDR, decrease in delay and throughput is maintained. This work is implemented and simulated on NS-2. Based on simulation results, the proposed protocol provides more consistent and reliable data transfer compared with general AODV, if there are misbehaving nodes in the MANET

Teaching and Clinical Efficiency: Competing Demands

IntroductionTeaching ability and efficiency of clinical operations are important aspects of physician performance. In order to promote excellence in education and clinical efficiency, it would be important to determine physician qualities that contribute to both. We sought to evaluate the relationship between teaching performance and patient throughput times.MethodsThe setting is an urban, academic emergency department with an annual census of 65,000 patient visits. Previous analysis of an 18-question emergency medicine faculty survey at this institution identified 5 prevailing domains of faculty instructional performance. The 5 statistically significant domains identified were: Competency and Professionalism, Commitment to Knowledge and Instruction, Inclusion and Interaction, Patient Focus, and Openness and Enthusiasm. We fit a multivariate, random effects model using each of the 5 instructional domains for emergency medicine faculty as independent predictors and throughput time (in minutes) as the continuous outcome. Faculty that were absent for any portion of the research period were excluded as were patient encounters without direct resident involvement.ResultsTwo of the 5 instructional domains were found to significantly correlate with a change in patient treatment times within both datasets. The greater a physician's Commitment to Knowledge and Instruction, the longer their throughput time, with each interval increase on the domain scale associated with a 7.38-minute increase in throughput time (90% confidence interval [CI]: 1.89 to 12.88 minutes). Conversely, increased Openness and Enthusiasm was associated with a 4.45-minute decrease in throughput (90% CI: −8.83 to −0.07 minutes).ConclusionSome aspects of teaching aptitude are associated with increased throughput times (Openness and Enthusiasm), while others are associated with decreased throughput times (Commitment to Knowledge and Instruction). Our findings suggest that a tradeoff may exist between operational and instructional performance.