Relief Networks Research Articles

Core network function placement in self-deployable mobile networks

Emerging mobile network architectures (e.g., aerial networks, disaster relief networks) are disrupting the classical careful planning and deployment of mobile networks by requiring specific self-deployment strategies. Such networks, referred to as self-deployable, are formed by interconnected rapidly deployable base stations that have no dedicated backhaul connection towards a traditional core network. Instead, an entity providing essential core network functionalities is co-located with one of the base stations. In this work, we tackle the problem of placing this core network entity within a self-deployable mobile network, i.e., we determine with which of the base stations it must be co-located. We propose a novel centrality metric, the flow centrality, which measures a node capacity of receiving the total amount of flows in the network. We show that in order to maximize the amount of exchanged traffic between the base stations and the core network entity, under certain capacity and load distribution constraints, the latter should be co-located with the base station having the maximum flow centrality. We first compare our proposed metric to other state of the art centralities. Then, we highlight the significant traffic loss occurring when the core network entity is not placed on the node with the maximum flow centrality, which could reach 55% in some cases.

Scalable simulation of a Disaster Response Agent-based network Management and Adaptation System (DRAMAS)

The objective of this paper is to advance the study of disaster response and recovery (generally, disaster relief) by providing tools and insights to agencies that work in disaster relief. This paper is built on extensive research of disaster relief literature and practice, and provides a comprehensive analysis of agency posturing following an extreme event. We present the Disaster Response Agent-based network Management and Adaptation System (DRAMAS) model, which uses stochastic processes to model the complex interactions between relief agencies of different sizes and capabilities. The DRAMAS simulation environment provide an excellent testing ground for hypotheses regarding relief agency partnerships, goals, roles, and prior involvement, by providing a depiction of the change in agency partnerships and resource investments following a disaster. The goal of this research is to expand the current body of knowledge and examine the fundamental principles of agency success during relief operations. We find that (a) larger relief networks tended to be less efficient at meeting the typical needs of the community, (b) having a relief network with more agents appeared to increase the time it took for a typical need, (c) having a high percentage of local agents resulted in an increased time for typical services, (d) a more dense network resulted in more effective identification of long-term needs and also improved services time, etc. Results from this work provide a path for improving our understanding of interagency partnerships and interaction, and could provide new insights into the behavior of agency networks in response to a disaster.

Smart PV grid to reinforce the electrical network

Photovoltaic (PV) became the new competitive energy resources of the planet and needs to be engaged in grid to break up the congestion in both Distribution and Transmission systems. The objective of this research is to reduce the load flow through the distribution and transmission equipment by 20%. This reduction will help in relief networks loaded equipment’s in all networks. Many projects are starting to develop in the GCC countries and need to be organized to achieve maximum benefits from involving the Renewable Energy Sources (RES) in the network.The GCC countries have a good location for solar energy with high intensity of the solar radiation and clear sky along the year. The opportunities of the solar energy is to utilize and create a sustainable energy resource for this region.Moreover, the target of this research is to engage the PV technology in such a way to lower the over loaded equipment and increases the electricity demand at the consumer’s side.

A Stochastic Optimization Model for Designing Last Mile Relief Networks

In this study, we introduce a distribution network design problem that determines the locations and capacities of the relief distribution points in the last mile network, while considering demand- and network-related uncertainties in the post-disaster environment. The problem addresses the critical concerns of relief organizations in designing last mile networks, which are providing accessible and equitable service to beneficiaries. We focus on two types of supply allocation policies and propose a hybrid version considering their different implications on equity and accessibility. Then, we develop a two-stage stochastic programming model that incorporates the hybrid allocation policy and achieves high levels of accessibility and equity simultaneously. We devise a branch-and-cut algorithm based on Benders decomposition to solve large problem instances in reasonable times and conduct a numerical study to demonstrate the computational effectiveness of the solution method. We also illustrate the application of our model on a case study based on real-world data from the 2011 Van earthquake in Turkey.

Adaptive and cognitive communication architecture for next-generation PPDR systems

In light of recent natural catastrophes and terrorist activities, it has become evident that new architectural approaches are needed for next generation public protection and disaster relief networks. These architectures should be adaptable to the conditions at the event site and resilient enough to operate under adverse conditions in an emergency. Furthermore, they should enable rapid gathering of crucial event data and its delivery to the responder units at the site as well as the command and control center that is off-site. In this article, we first examine the state of the art in areas related to communication in PPDR systems, and discuss the open research issues for each topic. Then we propose a novel architecture that meets the aforementioned requirements and relies on a novel device called an ICG. An ICG enables flexible use of the spectrum and facilitates data gathering from all lower-tier devices and relays this data to relevant units through the higher-tier public or commercial backhaul networks. Finally, we provide some results that justify the need for these devices in emergency scenarios.

Symptotics: a framework for estimating the scalability of real-world wireless networks

We present a framework for non-asymptotic analysis of real-world multi-hop wireless networks that captures protocol overhead, congestion bottlenecks, traffic heterogeneity and other real-world concerns. The framework introduces the concept of symptoticscalability to determine the number of nodes to which a network scales, and a metric called change impact value for comparing the impact of underlying system parameters on network scalability. A key idea is to divide analysis into generic and specific parts connected via a signature--a set of governing parameters of a network scenario--such that analyzing a new network scenario reduces mainly to identifying its signature. Using this framework, we present the first closed-form symptotic scalability expressions for line, grid, clique, randomized grid and mobile topologies. We model both TDMA and 802.11, as well as unicast and broadcast traffic. We compare the analysis with discrete event simulations and show that the model provides sufficiently accurate estimates of scalability. We show how our impact analysis methodology can be used to progressively tune network features to meet a scaling requirement. We uncover several new insights, for instance, on the limited impact of reducing routing overhead, the differential nature of flooding traffic, and the effect real-world mobility on scalability. Our work is applicable to the design and deployment of real-world multi-hop wireless networks including community mesh networks, military networks, disaster relief networks and sensor networks.

Humanitarian logistics network design under mixed uncertainty

In this paper, we address a two-echelon humanitarian logistics network design problem involving multiple central warehouses (CWs) and local distribution centers (LDCs) and develop a novel two-stage scenario-based possibilistic-stochastic programming (SBPSP) approach. The research is motivated by the urgent need for designing a relief network in Tehran in preparation for potential earthquakes to cope with the main logistical problems in pre- and post-disaster phases. During the first stage, the locations for CWs and LDCs are determined along with the prepositioned inventory levels for the relief supplies. In this stage, inherent uncertainties in both supply and demand data as well as the availability level of the transportation network's routes after an earthquake are taken into account. In the second stage, a relief distribution plan is developed based on various disaster scenarios aiming to minimize: total distribution time, the maximum weighted distribution time for the critical items, total cost of unused inventories and weighted shortage cost of unmet demands. A tailored differential evolution (DE) algorithm is developed to find good enough feasible solutions within a reasonable CPU time. Computational results using real data reveal promising performance of the proposed SBPSP model in comparison with the existing relief network in Tehran. The paper contributes to the literature on optimization based design of relief networks under mixed possibilistic-stochastic uncertainty and supports informed decision making by local authorities in increasing resilience of urban areas to natural disasters.

Profiling of Radio Propagation in VHF Band

The Very high frequency (VHF) band spans from 30 MHz to 300 MHz and is designated for public safety and disaster relief networks, FM radio broadcasting, TV broadcasting, air traffic control and many other mission critical services.  Most of these services often utilize the lower part of the VHF band and the coverage areas of such systems could be above hundreds of kilometers, which may require several transmitters operating in a quasi-synchronous mode. In addition, frequency reuse within this band for example, in the case of FM radio could result in excessive boarder area interference. Therefore, to minimize interference, even with the coexistence of these systems, there is a need to examine the behaviour of radio wave propagation in the band. Radio propagation models have been used extensively in interference analysis, coverage prediction and optimization. Most of the widely used models are location dependent, which, therefore, calls for continued efforts to ensure that location specific measurements are taken and used as planning tools, towards understanding the limitations arising from specific environmental conditions. In this work, Electromagnetic field (EM) strength measurements  were  conducted in Ilorin (Long 4o 36’ 25”E, Lat 8o 25’ 55’’N) and its environs within Kwara State, Nigeria, along some predefined routes, using dedicated Agilent N943C 100 Hz - 7 GHz spectrum analyzer. For each route, the measured received signal levels (RSLs) were obtained, profiled over the terrain and compared with simulated signal values obtained for COST 231, Egli, Hata and ILORIN models. A total of three transmitters were utilized; two in the lower VHF (LVHF) and one in the upper VHF (UVHF) bands. Results obtained showed that there is severe fading along all the routes considered, for all the broadcasting stations, with the highest signal level estimation observed for Egli, followed by COST 231, Hata and ILORIN model in that order. Measurements results also indicate that the received signal level is found to follow the terrain elevation for the models considered. However, the ILORIN model, which is a localized model was found to provide better predictions, despite the fact that the signal follows the terrain profile.

Humanitarian logistics: the role of logistics service providers

Purpose – In recent years, logistics service providers (LSPs) have become important players in the humanitarian field, providing support for NGOs and governments when they respond to major disasters. However, the academic literature on humanitarian logistics has not really explored the roles that LSPs play in relief supply chains. The purpose of this paper is to investigate the role of LSPs in humanitarian relief. Design/methodology/approach – The research uses a two-stage exploratory approach: first, it systematically reviews the humanitarian logistics literature to see the extent to which LSPs are taken into account. Then it analyses the web sites of leading LSPs to examine how they communicate about their role in humanitarian relief. Findings – This research produces some surprising findings. While the academic literature seems to neglect the roles of LSPs in humanitarian logistics, some major third-party firms highlight their roles in relief networks. A number of research propositions are presented de...

Optimal LAP Altitude for Maximum Coverage

Low-altitude aerial platforms (LAPs) have recently gained significant popularity as key enablers for rapid deployable relief networks where coverage is provided by onboard radio heads. These platforms are capable of delivering essential wireless communication for public safety agencies in remote areas or during the aftermath of natural disasters. In this letter, we present an analytical approach to optimizing the altitude of such platforms to provide maximum radio coverage on the ground. Our analysis shows that the optimal altitude is a function of the maximum allowed pathloss and of the statistical parameters of the urban environment, as defined by the International Telecommunication Union. Furthermore, we present a closed-form formula for predicting the probability of the geometrical line of sight between a LAP and a ground receiver.

PoC 멀티캐스트 성능향상 방안

PoC (Push-to-Talk over Cellular)는 이동통신망에서 SIP (Session Initiation Protocol) 기반의 VoIP (Voice over Internet Protocol) 기술을 이용하여 일-대-일 또는 일-대-다 통신을 지원하는 특징으로 인하여 재난망에서 이를 적용하기 위한 노력이 현재 시도중이다. 이러한 노력은 그룹 통신 지원이 핵심이며 이를 위한 표준화 제정이 진행중이다. 하지만, 현재 표준의 경우 재난망의 특징을 반영하지 않고 일반 PoC 서비스 중심의 그룹 통신을 지원하기 때문에 재난통신망 적용시 그룹이 특정 지역에 밀집한 경우 PoC 서버에 로드가 집중됨으로써 혼잡 및 이로 인한 지연이 길어지는 문제점이 존재한다. 이러한 문제점을 해결하기 위해서 본 논문에서는 특정 지역의 PoC 서버의 로드를 다수의 PoC 서버가 처리할 수 있도록 분산시킴으로써 강건성 및 전송 지연을 줄이기 위한 새로운 방안을 제안한다. 마지막으로 시뮬레이션을 통하여 성능 평가 결과를 제시한다. PoC (Push-to-Talk over Cellular) provides one-to-one as well as one-to-many communications with VoIP technology based on SIP over cellular networks. According to above property, PoC is considered as perscrptive technology for public protection for disaster relief networks. For this networks, group communication is the essential function. However, since current standardization process takes into general scenarios account without any consideration for mentioned networks, it have some problems in the point of adaptability. To solve above problem, in this paper, we propose how to reduce the overhead on the PoC server to reduce the transmission delay. Simulation results are shown to evaluate the improved performance.

Case study in disaster relief: A descriptive analysis of agency partnerships in the aftermath of the January 12th, 2010 Haitian earthquake

This study analyzes the disaster response and recovery efforts following the January 12th, 2010 Haitian earthquake through the eyes of 18 different relief agencies. Focusing on the formation and maintenance of partnerships after the catastrophic earthquake, this paper explores the concepts of cooperation, mutual understanding, and connectivity among agencies responding to the earthquake. The case study is based on results from interviews and interactions with 18 agencies during a month-long trip to Haiti in the summer of 2010. Of the agencies interviewed, it was found that agencies that had no partnerships or presence in Haiti prior to the earthquake were most likely to build new clinics, orphanages, and schools. Additionally, we found that agencies were more likely to develop new partnerships from new contacts rather than dormant contacts. By studying the partnerships between local and international agencies, it was found that their relationships were less stable than partnerships between international agencies. This study hopes to increase understanding and applicability of research in disaster relief networks by providing a new perspective into how agencies work together.

Risk approaches for delivering disaster relief supplies

We consider the problem of designing the logistic system to assure adequate distribution of relief aid in a post-natural-disaster situation, when damages to infrastructure may disrupt the delivery of relief aid. The problem is formulated as a multi-objective optimization problem, encompassing three objective functions of central interest in such problems. The first objective function is a measure of risk (various forms of such risk are analyzed). The second objective function measures the coverage provided by the logistic system in the distribution of relief aid to disaster victims. The third objective function represents total travel time. We focus on the risk of delivery tours for relief supplies, where risk here captures the threat that potential tours become impassable after the natural hazard event. In order to cope with a range of different natural disasters and policy objectives, we develop five approaches emphasizing different measures of tour-dependent risk. To cover both earthquake and flood risks, we consider correlated as well as uncorrelated risk measures. We develop a two-phase solution approach to reflect the dictates of real-world disaster relief motivating this analysis. The first phase generates potentially Pareto-optimal solutions to the overall multi-objective logistic design problem with respect to three objectives. For any given risk measure, the first-phase design problem is formulated as a multi-objective integer program and a memetic algorithm is proposed as the solution approach. The second phase is an enrichment procedure to generate a broader range of potentially Pareto-optimal alternatives. The suggested approach is tested on real-world data from the province of Manabi in Ecuador and the results associated with the different risk measures are analyzed to illustrate the value of the proposed approach for the design of disaster relief networks.

A City Living through Crisis: Jerusalem during World War I

This article aims to contribute to the literature on World War I in Palestine while studying the experience of the inhabitants of Jerusalem during the war. By focusing on a city and its residents, this article offers an analysis of the war from a dimension and lens yet to be explored in the history of Palestine. More specifically, the article will use relief networks in order to analyze not only the ways people experienced the war, but also as a way of exposing inter-communal dynamics between the different communities living in this mixed urban center.

Making humanitarian relief networks more effective: operational coordination, trust and sense making

Effective coordination of humanitarian assistance activities remains elusive. This paper briefly addresses some of the reasons for what is widely perceived as a coordination dilemma in humanitarian affairs and argues for a new conceptualisation of the issue. Rather than continue to request that more authority be vested in a single organisation to secure coordination through top-down control, it contends that it may be timely to consider whether relief agencies involved in an emergency should be reconceived as social networks and efforts made to achieve changes in their organizational cultures that encourage operational coordination across institutional lines. Since such labours imply the need to trust, this article explores what forms of trust might be employed to promote improved coordination among relief institutions and how those relationships could themselves be conceptualised. Finally, while acknowledging that coordination is not costless, it suggests that its effective pursuit may be advantageous even in scenarios where aid organisations balk at cooperating to secure it.

ACM SIGCOMM computer communication review

At some point in the future, how far out we do not exactly know, wireless access to the Internet will outstrip all other forms of access bringing the freedom of mobility to the way we access the we...

Optimization of pressure relief header networks: a linear programming formulation

The problem of optimal design of a pressure relief header network is addressed using an alternative set of decision variables represented by the lengths of pipe segments having different standard diameters. Although these variables have been largely employed for water distribution network design, until the present moment, they have not been applied to the design of pressure relief networks. The proposed formulation results in a linear programming problem easily solved by standard procedures. This optimization scheme is applied to the design of a network example from the literature. The solution found has a lower cost when compared to previous results.

Public Assistance and Labor Supply in Nineteenth-Century Lyon

Historians have presented the rise of the welfare state variously as a response to the problems engendered by industrialization and urbanization; a genuine humanitarian development; a victory for the working class; a capitalist conspiracy; and the product of progressive state bureaucrats.' Each of these schools of thought shares the assumption that at some point during or after the 1880s European municipal and national governments enacted, out of ideological and/or political mnotives, more generous social policies.2 Much of the conventional wisdom is based on the English model: harsh attitudes toward the poor hardened early in the nineteenth century and prevailed until late in the century, when unemployment was discovered, the distinction between the deserving and undeserving poor began to dissolve, and relief networks expanded. This article stands much of this accepted wisdom on its head in that it reverses the standard chronology and suggests that economic motives, rooted in labor-supply concerns, were equally, if not more, important than ideological or political motives in the formulation of general social policy. In Lyon, as elsewhere in France, the commitment to providing public assistance for

Flashing flow through relief lines, pipe breaks and cracks

This paper is primarily concerned with practical methods for sizing relief lines under compressible flashing flow conditions. An emphasis is placed on relief lines having tortuous geometries, the discussion also including relief networks, multicomponent mixtures and multiple choking. A design example is used to illustrate use of the methods and to provide some physical insight. Although attention is foccused on flow downstream of relief devices, reference is made to methods for estimating discharge rates through pressure relief valves and/or rupture discs. The applicability of the methods to the analysis of hypothetical pipe break scenarios is demonstrated by example and compared with some experimental data. Finally, the state-of-the-art regarding two-phase flow through cracks is briefly reviewed.