Numerous innovative heat recovery-to-power technologies have been resourcefully and technologically exploited to bridge the growing gap between energy needs and its sustainable and affordable supply.Among them,the pro...Numerous innovative heat recovery-to-power technologies have been resourcefully and technologically exploited to bridge the growing gap between energy needs and its sustainable and affordable supply.Among them,the proposed trilateral-cycle(TLC) power system exhibits high thermodynamic efficiency during heat recovery-to-power from low-to-medium temperature heat sources.The TLCs are proposed and analysed using n-pentane as working fluid for waste heat recovery-to-power generation from low-grade heat source to evaluate the thermodynamic efficiency of the cycles.Four different single stage TLC configurations with distinct working principles are modelled thermodynamically using engineering equation solver.Based on the thermodynamic framework,thermodynamic performance simulation and efficiency analysis of the cycles as well as the exergy efficiencies of the heating and condensing processes are carried out and compared in their efficiency.The results show that the simple TLC,recuperated TLC,reheat TLC and regenerative TLC operating at subcritical conditions with cycle high temperature of 473 K can attain thermal efficiencies of 21.97%,23.91%,22.07% and 22.9%,respectively.The recuperated TLC attains the highest thermodynamic efficiency at the cycle high temperature because of its lowest exergy destruction rates in the heat exchanger and condenser.The efficiency analysis carried out would assist in guiding thermodynamic process development and thermal integration of the proposed cycles.展开更多
The current phase of China-Africa relations in the UN system are underlined by the alignment of the three broad plans： the AU＇ Agenda 2063t the FOCAC action plans for the period 2015-18 and the UN Sustainable Develo...The current phase of China-Africa relations in the UN system are underlined by the alignment of the three broad plans： the AU＇ Agenda 2063t the FOCAC action plans for the period 2015-18 and the UN Sustainable Development Goals.展开更多
Localization of sensor nodes is crucial in Wireless Sensor Network because of applications like surveillance, tracking, navigation etc. Various optimization techniques for localization have been proposed in literature...Localization of sensor nodes is crucial in Wireless Sensor Network because of applications like surveillance, tracking, navigation etc. Various optimization techniques for localization have been proposed in literature by different researchers. In this paper, we propose a two phase hybrid approach for localization using Multidi- mensional Scaling and trilateration, namely, MDS with refinement using trilateration. Trilateration refines the estimated locations obtained by the MDS algorithm and hence acts as a post optimizer which improves the accuracy of the estimated positions of sensor nodes. Through extensive simulations, we have shown that the proposed algorithm is more robust to noise than previous approaches and provides higher accuracy for estimating the positions of sensor nodes.展开更多
Five-hundred-meter Aperture Spherical radio Telescope( FAST) is the largest sensitive single dish radio telescope in the world,in which the control and measurement of the feed is one crucial section of the FAST contro...Five-hundred-meter Aperture Spherical radio Telescope( FAST) is the largest sensitive single dish radio telescope in the world,in which the control and measurement of the feed is one crucial section of the FAST control system. Trilateration is presented to obtain three-dimensional coordinate for tracking feed focus cabin. Every three total stations chase prism movement to be attached on feed focus cabin and the prism position is determined from the measured distances based on the principle of trilateration. Therefore,feed position is determined from three prisms on the focus cabin. This study is to assess the accuracy and reliability of trilateration calculation on tracking focus cabin of FAST. Different arrangement of total stations on trilateration is theoretically studied. Through experiment,the proposed method shows that the accuracy is better than that of the polar coordinate measurement. The average root mean square error is lower than 0. 6 mm,which is found to have high accuracy and reliability.展开更多
Long Range Wide Area Network (LoRaWAN) in the Internet ofThings (IoT) domain has been the subject of interest for researchers. Thereis an increasing demand to localize these IoT devices using LoRaWAN dueto the quickly...Long Range Wide Area Network (LoRaWAN) in the Internet ofThings (IoT) domain has been the subject of interest for researchers. Thereis an increasing demand to localize these IoT devices using LoRaWAN dueto the quickly growing number of IoT devices. LoRaWAN is well suited tosupport localization applications in IoTs due to its low power consumptionand long range. Multiple approaches have been proposed to solve the localizationproblem using LoRaWAN. The Expected Signal Power (ESP) basedtrilateration algorithm has the significant potential for localization becauseESP can identify the signal’s energy below the noise floor with no additionalhardware requirements and ease of implementation. This research articleoffers the technical evaluation of the trilateration technique, its efficiency,and its limitations for the localization using LoRa ESP in a large outdoorpopulated campus environment. Additionally, experimental evaluations areconducted to determine the effects of frequency hopping, outlier removal, andincreasing the number of gateways on localization accuracy. Results obtainedfrom the experiment show the importance of calculating the path loss exponentfor every frequency to circumvent the high localization error because ofthe frequency hopping, thus improving the localization performance withoutthe need of using only a single frequency.展开更多
为了提高远距离无线电(Long Range Radio,LoRa)系统定位精度,提出利用接收信号强度指示(Received Signal Strength Indication,RSSI)测距和三边定位方法结合小波神经网络模型对LoRa节点进行定位。首先分析了RSSI测距、三边定位的原理和...为了提高远距离无线电(Long Range Radio,LoRa)系统定位精度,提出利用接收信号强度指示(Received Signal Strength Indication,RSSI)测距和三边定位方法结合小波神经网络模型对LoRa节点进行定位。首先分析了RSSI测距、三边定位的原理和实现方法,给出了基于RSSI测距方法求解LoRa网关与LoRa节点间距离的步骤。然后利用3层融合型小波神经网络搭建了LoRa节点定位模型,选取Morlet小波为隐含层神经元的激励函数,选取Sigmoid阈值函数为输出层函数,将LoRa节点到3个LoRa网关的距离作为输入层数据,节点定位模型转换并输出LoRa节点位置的归一化横坐标和纵坐标。最后利用LoRa网关模块和LoRa节点模块搭建了LoRa节点定位实验系统并进行了实验测试,通过实验数据分析得出了RSSI测距参数并利用三边定位算法和小波神经网络节点定位模型实现了待定位LoRa节点的精准定位。实验结果表明,所提算法的定位精度为1.033 m,优于四点质心定位算法和传统三边定位算法。展开更多
基金The University of Ilorin,Nigeria financially supported this research through scholarship grant from Tertiary Education Trust Fund
文摘Numerous innovative heat recovery-to-power technologies have been resourcefully and technologically exploited to bridge the growing gap between energy needs and its sustainable and affordable supply.Among them,the proposed trilateral-cycle(TLC) power system exhibits high thermodynamic efficiency during heat recovery-to-power from low-to-medium temperature heat sources.The TLCs are proposed and analysed using n-pentane as working fluid for waste heat recovery-to-power generation from low-grade heat source to evaluate the thermodynamic efficiency of the cycles.Four different single stage TLC configurations with distinct working principles are modelled thermodynamically using engineering equation solver.Based on the thermodynamic framework,thermodynamic performance simulation and efficiency analysis of the cycles as well as the exergy efficiencies of the heating and condensing processes are carried out and compared in their efficiency.The results show that the simple TLC,recuperated TLC,reheat TLC and regenerative TLC operating at subcritical conditions with cycle high temperature of 473 K can attain thermal efficiencies of 21.97%,23.91%,22.07% and 22.9%,respectively.The recuperated TLC attains the highest thermodynamic efficiency at the cycle high temperature because of its lowest exergy destruction rates in the heat exchanger and condenser.The efficiency analysis carried out would assist in guiding thermodynamic process development and thermal integration of the proposed cycles.
文摘The current phase of China-Africa relations in the UN system are underlined by the alignment of the three broad plans： the AU＇ Agenda 2063t the FOCAC action plans for the period 2015-18 and the UN Sustainable Development Goals.
文摘Localization of sensor nodes is crucial in Wireless Sensor Network because of applications like surveillance, tracking, navigation etc. Various optimization techniques for localization have been proposed in literature by different researchers. In this paper, we propose a two phase hybrid approach for localization using Multidi- mensional Scaling and trilateration, namely, MDS with refinement using trilateration. Trilateration refines the estimated locations obtained by the MDS algorithm and hence acts as a post optimizer which improves the accuracy of the estimated positions of sensor nodes. Through extensive simulations, we have shown that the proposed algorithm is more robust to noise than previous approaches and provides higher accuracy for estimating the positions of sensor nodes.
基金Supported by the National Natural Science Foundation of China(No.11273001,11373001,11703046)
文摘Five-hundred-meter Aperture Spherical radio Telescope( FAST) is the largest sensitive single dish radio telescope in the world,in which the control and measurement of the feed is one crucial section of the FAST control system. Trilateration is presented to obtain three-dimensional coordinate for tracking feed focus cabin. Every three total stations chase prism movement to be attached on feed focus cabin and the prism position is determined from the measured distances based on the principle of trilateration. Therefore,feed position is determined from three prisms on the focus cabin. This study is to assess the accuracy and reliability of trilateration calculation on tracking focus cabin of FAST. Different arrangement of total stations on trilateration is theoretically studied. Through experiment,the proposed method shows that the accuracy is better than that of the polar coordinate measurement. The average root mean square error is lower than 0. 6 mm,which is found to have high accuracy and reliability.
基金the ADEK Award for Research Excellence (AARE19-245)2019.
文摘Long Range Wide Area Network (LoRaWAN) in the Internet ofThings (IoT) domain has been the subject of interest for researchers. Thereis an increasing demand to localize these IoT devices using LoRaWAN dueto the quickly growing number of IoT devices. LoRaWAN is well suited tosupport localization applications in IoTs due to its low power consumptionand long range. Multiple approaches have been proposed to solve the localizationproblem using LoRaWAN. The Expected Signal Power (ESP) basedtrilateration algorithm has the significant potential for localization becauseESP can identify the signal’s energy below the noise floor with no additionalhardware requirements and ease of implementation. This research articleoffers the technical evaluation of the trilateration technique, its efficiency,and its limitations for the localization using LoRa ESP in a large outdoorpopulated campus environment. Additionally, experimental evaluations areconducted to determine the effects of frequency hopping, outlier removal, andincreasing the number of gateways on localization accuracy. Results obtainedfrom the experiment show the importance of calculating the path loss exponentfor every frequency to circumvent the high localization error because ofthe frequency hopping, thus improving the localization performance withoutthe need of using only a single frequency.
文摘为了提高远距离无线电(Long Range Radio,LoRa)系统定位精度,提出利用接收信号强度指示(Received Signal Strength Indication,RSSI)测距和三边定位方法结合小波神经网络模型对LoRa节点进行定位。首先分析了RSSI测距、三边定位的原理和实现方法,给出了基于RSSI测距方法求解LoRa网关与LoRa节点间距离的步骤。然后利用3层融合型小波神经网络搭建了LoRa节点定位模型,选取Morlet小波为隐含层神经元的激励函数,选取Sigmoid阈值函数为输出层函数,将LoRa节点到3个LoRa网关的距离作为输入层数据,节点定位模型转换并输出LoRa节点位置的归一化横坐标和纵坐标。最后利用LoRa网关模块和LoRa节点模块搭建了LoRa节点定位实验系统并进行了实验测试,通过实验数据分析得出了RSSI测距参数并利用三边定位算法和小波神经网络节点定位模型实现了待定位LoRa节点的精准定位。实验结果表明,所提算法的定位精度为1.033 m,优于四点质心定位算法和传统三边定位算法。
