Minimum Cell Connection in Line Segment Arrangements

We study the complexity of the following cell connection problems in segment arrangements. Given a set of straight-line segments in the plane and two points a and b in different cells of the induced arrangement: [(i)] compute the minimum number of segments one needs to remove so that there is a path connecting a to b that does not intersect any of the remaining segments; [(ii)] compute the minimum number of segments one needs to remove so that the arrangement induced by the remaining segments has a single cell. We show that problems (i) and (ii) are NP-hard and discuss some special, tractable cases. Most notably, we provide a near-linear-time algorithm for a variant of problem (i) where the path connecting a to b must stay inside a given polygon P with a constant number of holes, the segments are contained in P, and the endpoints of the segments are on the boundary of P. The approach for this latter result uses homotopy of paths to group the segments into clusters with the property that either all segments in a cluster or none participate in an optimal solution

On guarding real terrains: the terrain guarding and the blocking path problems

Locating a minimum number of guards on a terrain such that every point on the terrain is guarded by at least one of the guards is known as the Terrain Guarding Problem (TGP). In this paper, a realistic example of the terrain guarding problem is studied, involving the surveillance of a rugged geographical terrain by means of thermal cameras. A number of issues related to TGP are addressed with integer-programming models proposed to solve the problem. Also, a sensitivity analysis is carried out in which five fictitious terrains are created to see the effect of the resolution of the terrain, and of terrain characteristics, on coverage optimization and the required number of guards. Finally, a new problem, which is called the Blocking Path Problem (BPP), is introduced. BPP is about guarding a path on the terrain with a minimum number of guards such that the path blocks all possible infiltration routes. A discussion is provided about the relation of BPP to the Network Interdiction Problem (NIP), which has been studied extensively by the operations research community, and to the k-Barrier Coverage Problem, which has been studied under the Sensor Deployment Problem. BPP is solved via an integer-programming formulation based on a network paradigm

On Barrier Coverage in Wireless Camera Sensor Networks

[[abstract]]The paper proposed a distributed algorithm, namely CoBRA (Cone-based Barrier coveRage Algorithm), to achieve barrier coverage in wireless camera sensor networks (WCSNs). To the best understanding, CoBRA is the first algorithm which try to deal with the barrier coverage issue in WCSNs. Based on some observations, the basic concept of CoBRA is that each camera sensor can determine the local possible barrier lines according to the geographical relations with their neighbors. A sink in a WCSN initiates Barrier Request (BREQ) messages to form the possible barrier lines. Afterward, a barrier line is constructed by the Barrier Reply (BREQ) message initiated by another sink. CoBRA mainly includes three phases: Initial Phase, Candidate Selection Phase, and Decision Phase. In the Initial Phase, each camera sensor collects the local information of its neighbors and estimates the possible barrier lines. In the Candidate Selection Phase, a sink initiates the BREQ packets and forwards the BREQ packets to camera sensors. Camera sensors receiving the BREQ then reforward the BREQ packets to its neighbors who are capable of forming a barrier line. All camera sensors receiving the BREQ will forward the BREQ to their neighbors again in the same manner. Finally, in the decision phase, after the BREQ message is transmitted through the whole monitoring area, a BREP message is used by the sink to select a barrier line in a WCSN. The barrier coverage is achieved by finding the barrier line in the monitoring area. Experiment results show that CoBRA can efficiently achieve barrier coverage in WCSNs. Comparing to the ideal results, CoBRA can use fewer nodes to accomplish barrier coverage in random deployment scenarios.[[conferencetype]]國際[[conferencedate]]20100420~20100423[[iscallforpapers]]Y[[conferencelocation]]Perth, WA, Australi

Minimum cell connection in line segment arrangements

We study the complexity of the following cell connection problems in segment arrangements. Given a set of straight-line segments in the plane and two points a and b in different cells of the induced arrangement: (i) compute the minimum number of segments one needs to remove so that there is a path connecting a to b that does not intersect any of the remaining segments; (ii) compute the minimum number of segments one needs to remove so that the arrangement induced by the remaining segments has a single cell. We show that problems (i) and (ii) are NP-hard and discuss some special, tractable cases. Most notably, we provide a near-linear-time algorithm for a variant of problem (i) where the path connecting a to b must stay inside a given polygon P with a constant number of holes, the segments are contained in P, and the endpoints of the segments are on the boundary of P. The approach for this latter result uses homotopy of paths to group the segments into clusters with the property that either all segments in a cluster or none participate in an optimal solution

Rekomendasi Arsitektur Jaringan Nirkabel berbasis Hotspot untuk area pedesaan (Studi Kasus Pedesaan Jawa Timur Indonesia)

Abstrak— Penelitian ini bertujuan untuk mengetahui pola trafik internet pada beberapa lokasi yang diteliti. Pengamatan dilakukan selama dua belas (12) bulan. Data diolah dengan metode statistika untuk mendapatkan proyeksi pengguna internet dan kebutuhan titik hotspot. Penelitian menghasilkan rekomendasi kebutuhan hotspot dengan mempertimbangkan mobilitas pengguna internet dan countur lokasi. Rekomendasi perangkat berbeda pada tiap lokasi dari sisi geografis dan padatnya area. Line of Sight mempengaruhi kemampuan perangkat dalam memancarkan signal internet.Hasil penelitian menunjukkan terjadinya peningkatan pengguna internet pada hari raya umat Islam, Hal ini diduga karena mayoritas masyarakat pada lokasi tersebut muslim. Proyeksi pelanggan di 300 desa didapatkan minimum penetrasi 36,7% dan maksimal 85.2%. Rekomendasi sejumlah 940 Titik hotspot dengan area bandwith secara statik sebesar 3Mbps (aggregate download dan upload).  Penelitian memperhitungkan Link Budget perangkat backhoul tier 3 dengan frekuensi 24Ghz. Setiap  perangkat dapat menangani rata-rata jumlah device yang terkoneksi secara bersama sejumlah > 200 Device teknologi Wi-Fi (IEEE 802.11). Beban total trafik  > 1,6 GBPS. Rekomendasi Arsitektur  broadband wireless access Berbasis Hotspot Di Jawa Timur yaitu Surabaya 140 lokasi dengan 400 titik hotspot, Mojokerto sejumlah 70 lokasi dengan 210 titik hotspot. Pandaan sejumlah 80 lokasi dengan 240 titik hotspot Malang  43 lokasi dengan 90 titik hotspot.Kata kunci: Broadband Wireless Access, Hotspot, Line Of SightAbstract— This study aims to determine the pattern of internet traffic in several locations in Jawa Indonesia. Observations were made for twelve (12) months. Data is processed using statistical methods to obtain projections of internet users and hotspot needs. This study produces recommendations for hotspot needs by considering internet user mobility and location contours. Device recommendations vary by location in terms of geography and crowded areas. Line of Sight affects the ability of the device to emit internet signals. The results showed an increase in internet users on Muslim holidays. Projected customers in 300 villages have a minimum penetration of 36.7% and a maximum of 85.2%. The recommended number of 940 hotspots with a static area of 3Mbps (download aggregate and upload). This study takes into account the tier 3 Link Budget backhoul device with a frequency of 24Ghz. Each device can handle the average number of devices that are connected together by> 200 Wi-Fi technology devices (IEEE 802.11). Total traffic load> 1.6 GBPS. Architectural recommendations for broadband wireless access based on hotspots in East Java, Surabaya, 140 locations with 400 hotspots, Mojokerto with 70 locations with 210 hotspots. Pandaan a total of 80 locations with 240 Malang hotspots 43 locations with 90 hotspots Keywords: Broadband Wireless Access, Hotspot, Line Of Sigh

A wireless sensor network system for border security and crossing detection

The protection of long stretches of countries’ borders has posed a number of challenges. Effective and continuous monitoring of a border requires the implementation of multi-surveillance technologies, such as Wireless Sensor Networks (WSN), that work as an integrated unit to meet the desired goals. The research presented in this thesis investigates the application of topologically Linear WSN (LWSNs) to international border monitoring and surveillance. The main research questions studied here are: What is the best form of node deployment and hierarchy? What is the minimum number of sensor nodes to achieve k− barrier coverage in a given belt region? iven an appropriate network density, how do we determine if a region is indeed k−barrier covered? What are the factors that affect barrier coverage? How to organise nodes into logical segments to perform in-network processing of data? How to transfer information from the networks to the end users while maintaining critical QoS measures such as timeliness and accuracy. To address these questions, we propose an architecture that specifies a mechanism to assign nodes to various network levels depending on their location. These levels are used by a cross-layer communication protocol to achieve data delivery at the lowest possible cost and minimal delivery delay. Building on this levelled architecture, we study the formation of weak and strong barriers and how they determine border crossing detection probability. We propose new method to calculate the required node density to provide higher intruder detection rate. Then, we study the effect of people movement models on the border crossing detection probability. At the data link layer, new energy balancing along with shifted MAC protocol are introduced to further increase the network lifetime and delivery speed. In addition, at network layer, a routing protocol called Level Division raph (LD ) is developed. LD utilises a complex link cost measurement to insure best QoS data delivery to the sink node at the lowest possible cost. The proposed system has the ability to work independently or cooperatively with other monitoring technologies, such as drowns and mobile monitoring stations. The performance of the proposed work is extensively evaluated analytically and in simulation using real-life conditions and parameters. The simulation results show significant performance gains when comparing LD to its best rivals in the literature Dynamic Source Routing. Compared to DSR, LD achieves higher performance in terms of average end-to-end delays by up to 95%, packet delivery ratio by up to 20%, and throughput by up to 60%, while maintaining similar performance in terms of normalised routing load and energy consumption

Mitigating the Harm of Public Mass Shooting Incidents Through Situational Crime Prevention

This dissertation used environmental theoretical frameworks to understand how public mass shooting incidents are impacted by aspects of the crime situation and opportunity. Predatory, public shootings perpetrated by individuals with evidence of mass intent were examined in the United States between 1966 and 2019. This project progressed in several distinct steps with discrete aims: (1) establish an open source database of public mass shooting incidents meeting definitional criteria; (2) perform statistical analysis, including latent class analysis, regression modeling, and structural equational modeling to assess research questions; and (3) perform comparative case studies and crime script analysis to assess situational crime prevention failure or success in eight purposively selected cases. Two research questions, guided by pathway to violence literature, rational choice perspective, and situational crime prevention, were examined: (1) can public mass shooting perpetrators be sorted into meaningful classes according to preparatory and warning signs behaviors?; and (2) how do the built environment and situational guardianship structure of the public mass shooting location influence incident casualties and severity outcomes? Results from this mixed methods study indicate that public mass shooting perpetrators fall into three distinct behavioral classes characterized by different probabilities of warning signs behaviors. Next, there is a protective role of holistic situational crime prevention for mitigating harm of public mass shooting incidents. Protective environmental design exerted a contradictory effect on incident outcomes, mediated by perpetrator and victim behaviors during the shooting. Case studies revealed that failure is often due to human error in implementation of established SCP protocols, rather than a lack of SCP protocols. Implications for prevention and harm mitigation are discussed