Clustering management technique of hot spot area based on distance weight in WSNs

Almutairi, Fahad Muaybid A Sungkyunkwan University 2015 국내석사

Nodes can sense adjacent area, local processing and wireless communication because of recent technical improvement in wireless networks. We call the network which use the device with small size, low price and low power wireless sensor networks (WSNs). WSNs are composed of many sensor nodes for monitoring or collecting data from specific area of network. The scattered sensor nodes detect environmental phenomena and generate sensing data of environment like temperature, humidity, sound and so on. These created sensing data are sent to the base station (BS) and sink node over the wireless networks which support interface, like Internet and satellite, to end users. In WSNs, data transmission of sensor nodes is multi-hop manner because of limited transmission range. Sensor nodes can connect external networks through sink node or BS. That means that nodes near BS always relays sensing data from other nodes. This area is called Hop Spot Area and the nodes in hot spot are Hot Spot Nodes (HSNs). HSNs usually consume more energy for this. To set up local clusters in WSNs, it should consider energy consumption near sink node or BS. To achieve this, we have to find factors which location of sensor nodes can affect energy consumption like distance weight. Thus, this paper found two factors to affect energy consumption of nodes. One thing is local cluster size. Another thing is location of cluster heads in WSNs. Through them, we proposed novel clustering management technique which can balance between HSNs and others. 무선 센서 네트워크(WSNs) 환경에서 중요한 이슈는 노드 간 통신 방식을 통해 효율적인 에너지 밸런스를 유지하는 것이다. 그러나 무선 센서 네트워크 특성상, 노드 간의 통신으로 인해 전체적으로 노드들의 에너지 소모율을 맞추는 것은 어렵다. 이유는 다음과 같다. 센서노드들이 싱크노드로 데이터를 직접 전송하는 방식은 노드들 간의 거리에 의한 차이 때문에 싱크노드와 먼 거리의 노드들이 먼저 에너지 소모율이 낮은 경우가 발생한다. 즉, 센서노드들이 멀티홉 전송방식으로 싱크노드로 데이터를 전송하면 싱크노드와 가까이 배치된 노드들이 먼저 에너지 소모율이 높아지는 경우가 발생한다. 이처럼 노드들의 에너지가 다른 노드들 보다 상대적으로 빠르게 소모되어 노드가 죽는 경우 핫스팟 노드(Hot Spot Node: HSN)라 정의한다. 그리고 HSN이 모인 영역을 핫스팟 영역(Hot Spot Area:HSA) 라 정의한다. 따라서 HSN을 고려한 노드의 균등한 에너지 소비는 매우 중요한 이슈이다. 위와 같이 균등한 에너지 소비를 유지하기 위해서는 HSN이 발생할 수 있는 지역에 대한 가중치를 계산해야만 한다. 가중치를 계산하는 이유는 핫스팟 영역에 대한 관리를 효율적으로 하기 위함이다. 노드 메시지는 싱크 노드와 거리가 가장 먼 노드, 홉 카운트가 먼 노드,가 다른 노드로부터 메시지를 전달 가능성이 적다. 반면에 홉수가 가장 적은 노드는 다른 이웃 노드들로부터 메시지를 전달 받을 가능성이 높다. 따라서 홉 거리에 따른 가중치 k는 홉 수와 반대로 높아진다. 즉, 싱크노드와 가까운 노드들은 다른 노드로부터 메시지를 전달하는 추가적인 에너지 소모를 할 가능성이 많다. 센서 네트워크에서는 각 노드의 에너지 소모가 균등하게 소모되는 경우에 네트워크의 수명이 가장 길다. 따라서 본 논문에서는 HSN의 에너지 소비를 고려하여 클러스터 헤드를 위치를 정하는 알고리즘을 제안한다. 위 제안한 기법을 통해 효율적으로 클러스터 헤드 위치를 계산하였고 이를 검증하기 위해 MR-LEACH 기법과 ACT 기법을 비교하여 제안한 방법의 효율성을 검증 하였다.

Action Research for Behavioral Theory Building:Six Sigma Success Factors

Almutairi, Thamer Nasser Washington State University ProQuest Dissertations 2020 해외박사(DDOD)

We conducted action research Six Sigma projects in the Tri-Cities, Washington, USA, region. These projects generated new theories. These theories were supported by the analysis of a survey of 736 manufacturers in Canada and the United States.First theory, the degree of project uncertainty moderates the impact of improved strategic project selection on Six Sigma project performance. we determined that this moderating effect should be negative since greater uncertainty in the project environment should lead to the project team sacrificing strategic project selection for more short-term results that are easier to attain in a reasonable timeframe and budget.Second, we conjectured a new construct Simultaneity of Thought for project team members that moderates the effects of the Use of Improvement Specialists and the Use of Structured Methods on project performance. We discovered also that Simultaneity of Thought is a significant associate of success, but not in a moderating fashion.Third, we show that these projects generated theory that matches the theories tested in the general team project management literature. the primary aim of this work is to perform a replication test of these theories in a Six Sigma project management environment.

Risk-aware virtual resource management for access controlled cloud data centers

Almutairi, Abdulrahaman A Purdue University 2015 해외박사(DDOD)

For economic benefits and efficient management of resources, organizations are increasingly moving towards the paradigm of "cloud computing" through which they are allowed on-demand delivery of hardware, software and data as services. Multi- tenancy and virtualization features of cloud computing enhance resource utilization and lower the cloud provider total cost of hosting customers data centric services. However, cloud vulnerabilities associated with its software and services pose many security challenges which are particularly exacerbated by multi-tenancy that allows sharing of resources among potentially untrusted tenants in access controlled cloud datacenters. Such vulnerabilities can result in an increased risk of data and information leakage. To mitigate this risk, we propose eefficient risk-aware virtual resource assignment mechanisms for cloud multi-tenant environment. In particular, we introduce the notion of sensitivity in datacenters with the objective to minimize the risk of leakage of data and its associated knowledge. Generally, the risk should not exceed in high sensitivity datacenters in comparison to low sensitivity datacenters. We present various assignment heuristics and compare their relative performance. In addition we present a distributed access control architecture that provides secure interoperation within a multi-cloud environment.

Distributed Multiple Access for OFDMA Femtocells

Almutairi, Abdulmohsen University of Washington 2014 해외박사(DDOD)

Demand for data services in cellular networks is growing exponentially, due to the proliferation of high-end, multimedia-enabled mobile devices. To meet this challenge, cellular operators are moving toward a heterogeneous network architecture consisting of macrocells for wide-area coverage and smaller cells such as femtocells for capacity boost in local hotspots. The primary problem in such heterogeneous networks is mitigating inter-cell interference especially in dense deployments of residential femtocells. Traditionally, interference in wide-area cellular networks has been studied from a multi-cell resource allocation perspective, where radio resources, e.g. power, bandwidth, are allocated to different cells to reduce interference. This approach generally assumes a fully loaded network (i.e. many simultaneous active users in a cell) where the system performance is insensitive to the activity of a single user. This assumption is not suitable for femtocells which are designed to serve very few users and thus lacks the presumed traffic aggregation. In this thesis, we first discuss the infeasibility of applying the classical multi-cell resource allocation framework to the femtocell case. Then, we motivate the case of using distributed, random access protocols as apposed to centralized interference mitigation techniques in the context of LTE femtocells. For this, we employ queuing analysis to compare the performance of centralized resource allocation schemes represented by an ideal power control to the performance of a simple random access protocols. The results show that, with a high probability, a simple un-optimized random access protocol such as Aloha would perform much better than an optimized power controlled network in most of the unsaturated traffic scenarios. This result serves as a strong motivation for the design of OFDMA-aware random access protocols that utilize the inherent frequency diversity of OFDMA to improve the MAC performance. Next, we analyze OFDMA-Aloha which is the simplest protocol that utilize the frequency-dimension in OFDMA to improve random access performance. The protocol attempts to reduce the packet retransmission time using collision resolution over the frequency domain by switching subchannels randomly after each collision. However, this comes at the expense of expanded time scale, or larger slot size due to lower channel rates. We showed that when the network is lightly loaded, the reduction in the collision rate outweighs the effect of expanded slot size thus in these situations OFDMA-Aloha enjoys smaller packet delays than the single channel Aloha. Then, we propose the Exponential Backoff in Frequency (EBF) algorithm to address the case when multiple packets need to be transmitted over multiple subchannels simultaneously. Instead of spreading the packets uniformly over K subchannels as would be done in a multichannel variant of Aloha (K-Aloha), the EBF algorithm keeps packet transmissions clustered at few frequency branches using a synchronized binary tree branching process over the K subchannels. Collisions are handled by reducing the accessed bandwidth exponentially and using an access probability that is inversely proportional to the accessed bandwidth. Analysis of a lightly loaded network, shows that EBF enjoys considerably less packet delay compared to the basic K-Aloha protocol. Finally, we propose the OFDM-based Reservation Random access (OFDM-RR) protocol that utilizes the frequency-dimension in a different way. In this protocol, reservation requests are transmitted on randomly selected subchannels and the indices of these subchannels are then used to create an implicit ordering among competing nodes for conflict resolution. Our analysis shows that beyond some critical value of the network load, OFDM-RR significantly improves the system throughput compared to the canonical Reservation-Aloha (R-Aloha) protocol.

Efficient algorithms for learning correlations in large-scale wireless data

Almutairi, Abdullah University of Florida 2012 해외박사(DDOD)

Wireless mobile networks are experiencing tremendous growth and increased presence. Data collected for mobile users can be effectively used to design more effective networks as well as provide more effective services to the users. In particular, understanding the behavioral model of the users in the wireless network can help in designing efficient context-aware protocols and services that revolve around the target users. In this dissertation, we explore the use of data mining techniques for analyzing wireless data. Wireless data has many characteristics that make it very challenging from a data mining perspective. In particular, the challenges revolve around a large number of spatio-temporal dimensions representing mobility of the users, their access patterns from multiple websites and time domain. For each of the dimensions, the number of possible values can be from thousands to millions. Further, these values may have spatial and temporal relationships. We present a novel algorithm that reduces the overall time complexity of finding meaningful website access patterns in wireless data. The overall time reduction is by several orders of magnitude resulting in the application of these techniques to significantly larger size problems. When data is available for multiple locations, it is very challenging to develop multiple models that each represent the different behavior of users at the different locations but also capture the commonalities of behavior between multiple locations. We propose a Global Local model that captures the above ideas and can be used to understand the relationship of different locations based on multiple users’ mobile behavior. The study is extended to the temporal attributes of the data to learn both the temporal and spatio-temporal correlations present in the wireless data. To find these correlations we propose a Multi-Dimensional Hierarchical Co-Clustering (MDHCC) method.

Effect of droplet size on the behavior and characteristics of emulsified acid

Almutairi, Saleh H Texas A&M University 2008 해외박사(DDOD)

Emulsified acids have been extensively used in the oil industry since 1933. Most of the available research and publications discussed mainly the application of emulsified acid in the field. A fair number of the published work also discussed in depth some of the emulsified acid properties such viscosity, stability and reactivity. However, all of the available research discussed the emulsified acid without sufficient details of its preparation. Beside their chemical composition, the ways emulsified acids are prepared cause significant differences in their physical properties. The characterization of emulsified acid by its droplet size and size distribution complements its chemical composition and gives the emulsified acid a unique description and thus reproducible properties. No previous study considered the impact of the droplet size on the characteristics and properties of emulsified acid. Therefore, the main objective of this research is to study the effects of the droplet size on various properties of emulsified acid such as viscosity, stability and reactivity. Results showed that the droplet size and size distribution have a strong effect on the stability, viscosity and diffusion rate of the emulsified acid. The results of this work are important because knowledge of the effect of the droplet size on major design parameters will guide the way emulsified acid is prepared and applied in the field.

Social Media Advertising: Marketing E-Cigarettes on Instagram to Adolescents & Emerging Adults in the United States

Almutairi, Nasser Nka N. Alsadoni Michigan State University ProQuest Dissertations & 2021 해외박사(DDOD)

While the proliferation of social media brought great opportunities for marketers and advertisers, these platforms have become focal for public health risks, especially with younger populations. Underage e-cigarette use has become a public health epidemic in the United States, especially among adolescents. Per the Food and Drug Administration (FDA, 2018b), the e-cigarette industry is aggressively and successfully promoting e-cigarettes among underage populations through product design, variety of flavors, social media marketing, and advertising campaigns (Bronstad, 2020, February 19; Betz, 2020, February 25). With limited research examining the different strategies implemented to attract and target adolescents and young adults, the current study investigated how underage youth and young adults can access and get targeted by e-cigarette brands and retailers on the popular social media platform, Instagram. To do so, the study used fictitious Instagram user profiles of varying ages (13 vs. 19 vs. 25 years old) and two forms of user engagement (post vs. reach) over a three-week intervention period. The goal of the study is to document whether or not users below the legal purchase age (i.e., 13) are able to access e-cigarette content on Instagram, and more importantly, what types of messages and sponsored content will they receive and be targeted with over the intervention period. Findings showed e-cigarette retailers and brands are actively targeting adolescents and emerging adults through Instagram. By providing promotional and marketing content on Instagram through open accessibility, direct private communication messages, and engagement with users' content regardless of promotional and age legal restrictions.

Delocalized pi-electron systems: Towards actuators and switches

Almutairi, Adah University of California, Riverside 2005 해외박사(DDOD)

The underlying theme in this dissertation is the study of structure-property relationships of pi-electron systems, and thereby determining the functions that may arise from these properties. We primarily describe our findings on the structure-property relationship of ortho oligo aryls and our proposed application of these helical systems as Single Molecule, or Intrinsic Electromechanical Actuators. Electromechanical actuation (EMA) is the conversion of electrical to mechanical energy. Conducting polymer EMAs (CP-EMAs) are a well-known class of functional conjugated polymers, that can generate up to 100 times more force than natural muscle for a given cross-section, and up to three times the power to mass ratios. Ortho oligo thiophenes, in general, have shown a propensity for helicity, coupled with redox induced dimensional changes that mimic the movement of a spring. We show, as proof of concept, their utility as spring-like Intrinsic Electromechemical Actuators, which function at lower voltages, allowing for higher efficiencies, faster response rates, and higher fatigue resistance.