• Title/Summary/Keyword: consumption capability

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Performance Optimization and Analysis on P2P Mobile Communication Systems Accelerated by MEC Servers

  • Liang, Xuesong;Wu, Yongpeng;Huang, Yujin;Ng, Derrick Wing Kwan;Li, Pei;Yao, Yingbiao
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.16 no.1
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    • pp.188-210
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    • 2022
  • As a promising technique to support tremendous numbers of Internet of Things devices and a variety of applications efficiently, mobile edge computing (MEC) has attracted extensive studies recently. In this paper, we consider a MEC-assisted peer-to-peer (P2P) mobile communication system where MEC servers are deployed at access points to accelerate the communication process between mobile terminals. To capture the tradeoff between the time delay and the energy consumption of the system, a cost function is introduced to facilitate the optimization of the computation and communication resources. The formulated optimization problem is non-convex and is tackled by an iterative block coordinate descent algorithm that decouples the original optimization problem into two subproblems and alternately optimizes the computation and communication resources. Moreover, the MEC-assisted P2P communication system is compared with the conventional P2P communication system, then a condition is provided in closed-form expression when the MEC-assisted P2P communication system performs better. Simulation results show that the advantage of this system is enhanced when the computing capability of the receiver increases whereas it is reduced when the computing capability of the transmitter increases. In addition, the performance of this system is significantly improved when the signal-to-noise ratio of hop-1 exceeds that of hop-2.

Effect of Green Transformational Leadership and Organizational Environmental Culture on Manufacturing Enterprise Low Carbon Innovation Performance

  • Li, Liang;Fuseini, Joseph;Tan, MeiXuen;Sanitnuan, Nuttida
    • Asia Pacific Journal of Business Review
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    • v.6 no.2
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    • pp.27-60
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    • 2022
  • Previous studies stated that low carbon innovation performance could be influenced by government regulations and the green market, which is the new trend of consumer consumption in the present time, mainly focusing on external factors. Before study augured that low carbon innovation performance could be driven by internal and external factors of cooperation such as institutional pressure, stakeholder pressure, and innovation resources. However, the study of green transformational leadership and organizational environmental culture on low carbon innovation performance is rare, especially in Chinese manufacturing, as well as the effect of influencing factors of TPB model: environmental attitude, subjective norm, and perceived behavior capability on low carbon innovation performance. Previous studies mostly used the TPB model for predicting individual behavior. This study established a theoretical model combining the TPB model with green transformational leadership and organizational environmental culture of Chinese automobile manufacturing on low carbon innovation performance. This study consists of two sections of research methodology: section 1 related to questionnaire design and data collection. We established a questionnaire and distributed it online, targeting responses from the managerial level working in Chinese automobile manufacturing. Eventually, 155 valid questionnaires were used for analysis. Section 2 involved data analysis using statistical software. Reliability and data validity was examined by reliability analysis and factor analysis. Correlations and convergent validity analyses were applied, and structural equation modeling was conducted to test the proposed hypotheses. The findings indicated that green transformational leadership, organizational environmental culture, and essential factors of TPB model; environmental attitude, subjective norm and perceived behavior capability positively affect low carbon innovation performance. In addition, the indirect effect of green transformational leadership was tested and found that organizational environmental culture and TPB factors mediated the relationship between transformational leadership and low carbon innovation performance.

Study on reduction of power consumption in GPS embedded terminals with periodic position fix (GPS 단말기에서의 주기적 위치 측위에 따른 전력소모 최소화 방안 연구)

  • Bae, Seong-Soo;Kim, Dong-Ku;Kim, Tae-Min;Han, Chang-Moon;Kim, Byeong-Cheol
    • Journal of Advanced Navigation Technology
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    • v.11 no.3
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    • pp.239-251
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    • 2007
  • This thesis is about the reduction of the power consumption in GPS embedded terminals with periodic position fix to improve the time delay of position determination. In order to improve time delay of position determination during the wireless terminal is powered on, it needs to be set such that it can be periodically recalibrated by the GPS and those recalibrated values need to be saved in the terminal's memory so that it can reduce the time delay from the request of location. By using the trace of the information that's been saved in the terminal's memory, it can be set so that it'll be easier to determine whether the wireless terminal has gone into buildings and have the capability of checking if it has gone into a specific building. Likewise, while the terminal is turned on, in order calibrate the location, it needs to continuously work the GPS engine which leads to a rapid decrease in terminal's idle time. This thesis proposes some solutions regarding these issues - reducing 20 ~ 30% of the battery consumption for GPS visible situation that can occur when the wireless terminal periodically calibrates its location to determine the in-building status, and extending the idle time of the terminal by flexibly using the suggested GPS calibration time method according to wireless terminal's mobility.

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Development of Sensor Network Simulator for Estimating Power Consumption and Execution Time (전력소모량 및 실행시간 추정이 가능한 센서 네트워크 시뮬레이터의 개발)

  • Kim, Bang-Hyun;Kim, Tae-Kyu;Jung, Yong-Doc;Kim, Jong-Hyun
    • Journal of the Korea Society for Simulation
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    • v.15 no.1
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    • pp.35-42
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    • 2006
  • Sensor network, that is an infrastructure of ubiquitous computing, consists of a number of sensor nodes of which hardware is very small. The network topology and routing scheme of the network should be determined according to its purpose, and its hardware and software may have to be changed as needed from time to time. Thus, the sensor network simulator being capable of verifying its behavior and estimating performance is required for better design. Sensor network simulators currently existing have been developed for specific hardwares or operating systems, so that they can only be used for such systems and do not provide any means to estimate the amount of power consumption and program execution time which are major issues for system design. In this study, we develop the sensor network simulator that can be used to design and verify various sensor networks without regarding to types of applications or operating systems, and also has the capability of predicting the amount of power consumption and program execution time. For this purpose, the simulator is developed by using machine instruction-level discrete-event simulation scheme. As a result, the simulator can be used to analyze program execution timings and related system behaviors in the actual sensor nodes in detail. Instruction traces used as workload for simulations are executable images produced by the cross-compiler for ATmega128L microcontroller.

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A Rendezvous Node Selection and Routing Algorithm for Mobile Wireless Sensor Network

  • Hu, Yifan;Zheng, Yi;Wu, Xiaoming;Liu, Hailin
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.12 no.10
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    • pp.4738-4753
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    • 2018
  • Efficient rendezvous node selection and routing algorithm (RNSRA) for wireless sensor networks with mobile sink that visits rendezvous node to gather data from sensor nodes is proposed. In order to plan an optimal moving tour for mobile sink and avoid energy hole problem, we develop the RNSRA to find optimal rendezvous nodes (RN) for the mobile sink to visit. The RNSRA can select the set of RNs to act as store points for the mobile sink, and search for the optimal multi-hop path between source nodes and rendezvous node, so that the rendezvous node could gather information from sensor nodes periodically. Fitness function with several factors is calculated to find suitable RNs from sensor nodes, and the artificial bee colony optimization algorithm (ABC) is used to optimize the selection of optimal multi-hop path, in order to forward data to the nearest RN. Therefore the energy consumption of sensor nodes is minimized and balanced. Our method is validated by extensive simulations and illustrates the novel capability for maintaining the network robustness against sink moving problem, the results show that the RNSRA could reduce energy consumption by 6% and increase network lifetime by 5% as comparing with several existing algorithms.

Energy-Efficient Real-Time Task Scheduling for Battery-Powered Wireless Sensor Nodes (배터리 작동식의 무선 센서 노드를 위한 에너지 효율적인 실시간 태스크 스케줄링)

  • Kim, Dong-Joo;Kim, Tae-Hoon;Tak, Sung-Woo
    • Journal of Korea Multimedia Society
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    • v.13 no.10
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    • pp.1423-1435
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    • 2010
  • Building wireless sensor networks requires a constituting sensor node to consider the following limited hardware resources: a small battery lifetime limiting available power supply for the sensor node, a low-power microprocessor with a low-performance computing capability, and scarce memory resources. Despite such limited hardware resources of the sensor node, the sensor node platform needs to activate real-time sensing, guarantee the real-time processing of sensing data, and exchange data between individual sensor nodes concurrently. Therefore, in this paper, we propose an energy-efficient real-time task scheduling technique for battery-powered wireless sensor nodes. The proposed energy-efficient task scheduling technique controls the microprocessor's operating frequency and reduces the power consumption of a task by exploiting the slack time of the task when the actual execution time of the task can be less than its worst case execution time. The outcomes from experiments showed that the proposed scheduling technique yielded efficient performance in terms of guaranteeing the completion of real-time tasks within their deadlines and aiming to provide low power consumption.

Parametric modeling and shape optimization of four typical Schwedler spherical reticulated shells

  • Wu, J.;Lu, X.Y.;Li, S.C.;Xu, Z.H.;Li, L.P.;Zhang, D.L.;Xue, Y.G.
    • Structural Engineering and Mechanics
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    • v.56 no.5
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    • pp.813-833
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    • 2015
  • Spherical reticulated shells are widely applied in structural engineering due to their good bearing capability and attractive appearance. Parametric modeling of spherical reticulated shells is the basis of internal analysis and optimization design. In the present study, generation methods of nodes and the corresponding connection methods of rod elements are proposed. Modeling programs are compiled by adopting the ANSYS Parametric Design Language (APDL). A shape optimization method based on the two-stage algorithm is presented, and the corresponding optimization program is compiled in FORTRAN environment. Shape optimization is carried out based on the objective function of the minimum total steel consumption and the restriction condition of strength, stiffness, slenderness ratio, stability. The shape optimization of four typical Schwedler spherical reticulated shells is calculated with the span of 30 m~80 m and rise to span ratio of 1/7~1/2. Compared with the shape optimization results, the variation rules of total steel consumption along with the span and rise to span ratio are discussed. The results show that: (1) The left and right rod-Schwedler spherical reticulated shell is the most optimized and should be preferentially adopted in structural engineering. (2) The left diagonal rod-Schwedler spherical reticulated shell is second only to left and right rod regarding the mechanical behavior and optimized results. It can be applied to medium and small-span structures. (3) Double slash rod-Schwedler spherical reticulated shell is advantageous in mechanical behavior but with the largest total weight. Thus, this type can be used in large-span structures as far as possible. (4) The mechanical performance of no latitudinal rod-Schwedler spherical reticulated shell is the worst and with the second largest weight. Thus, this spherical reticulated shell should not be adopted generally in engineering.

Explaining One Less Nuclear Energy Policy from Governance Perspective: Energy Transition and Effectiveness of Urban Energy Policy (대안적 에너지 정책에 대한 탐색: 서울시 원전하나 줄이기 정책과 거버넌스의 역할)

  • Lee, Joo Hun
    • Korean Journal of Legislative Studies
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    • v.23 no.1
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    • pp.151-185
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    • 2017
  • Seoul's One Less Nuclear Power Plant is the major urban energy policy launched in April 2012. Its effort to respond to climate change and energy crisis in the aftermath of the Fukushima nuclear accident turned out very successful, considering huge decrease of energy consumption. However, the question of how the cut of energy consumption was possible remains unanswered. This paper introduces the concept of urban governance capacity as the cause of the success. It is the managing and governing capability to maintain the logical consistency policy system, comprising of policy perception, goals, policy tools and evaluation. Without this logical correspondence between the policy factors, any system including energy regime easily falls apart during the systemic transitional period. Governance capacity provides the integrating framework, so that the system as a whole maintains the internal homeostasis.

Performance of a Refrigerant Heating Type Heat Pump by Changing of Driving Devices and Heat Exchangers (구동장치 및 열교환기 변경에 따른 냉매가열식 열펌프의 성능특성)

  • Park, Youn-Cheol;Kim, Sang-Hyuk;Kim, Ji-Young
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.20 no.1
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    • pp.49-56
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    • 2008
  • When the outdoor air temperature decreased less than the freezing temperature, frost forms at the surface of heat exchangers and it makes the performance degradation of a heat pump system. In this study, a heat pump system has been developed which has a refrigerant heating device as an auxiliarly heating equipment. To reduce power consumptions of the system, a liquid pump, rather than a compressor, was used to drive refrigerant in the heat pump cycle. Ratio of refrigerant mass flow between a refrigerant heating heat exchanger(GHX) and a outdoor plate heat exchanger(PHX) was varied and the system performance was measured and analyzed. As results, when the refrigerant flow rate to the GHX was decreased, the system performance is decreased due to heat absorption capability restriction of the GHX and small variation of the power consumption in the compressor. The effect on the evaporating and condensing pressure by the distribution ratio of the refrigerant to the each heat exchanger is small compare to the effect by the frequency change in the compressor. When the compressor was replaced by the liquid pump, the capacity of the system decreased a little, however the power consumption decrease approximately 80% compare with the power used in the compressor.

Energy-Efficient MEC Offloading Decision Algorithm in Industrial IoT Environments (산업용 IoT 환경에서 MEC 기반의 에너지 효율적인 오프로딩 결정 알고리즘)

  • Koo, Seolwon;Lim, YuJin
    • KIPS Transactions on Computer and Communication Systems
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    • v.10 no.11
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    • pp.291-296
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    • 2021
  • The development of the Internet of Things(IoT) requires large computational resources for tasks from numerous devices. Mobile Edge Computing(MEC) has attracted a lot of attention in the IoT environment because it provides computational resources geographically close to the devices. Task offloading to MEC servers is efficient for devices with limited battery life and computational capability. In this paper, we assumed an industrial IoT environment requiring high reliability. The complexity of optimization problem in industrial IoT environment with many devices and multiple MEC servers is very high. To solve this problem, the problem is divided into two. After selecting the MEC server considering the queue status of the MEC server, we propose an offloading decision algorithm that optimizes reliability and energy consumption using genetic algorithm. Through experiments, we analyze the performance of the proposed algorithm in terms of energy consumption and reliability.