<div style="text-align:justify;"> Aiming at the problems of LED-based visible light positioning system such as unstable illumination, Lambertian model transmission limitation, large positioning error, ...<div style="text-align:justify;"> Aiming at the problems of LED-based visible light positioning system such as unstable illumination, Lambertian model transmission limitation, large positioning error, etc., it is proposed to use PWM to drive the LED, use the curve fitting method to obtain the ranging model, and estimate the target position according to the trilateral algorithm. A positioning system platform based on the microcontroller MiniSTM32 was built to test the performance of the transceiver circuit. The experimental results showed that the positioning error of less than 3 cm was achieved in a space of 80 cm × 80 cm × 80 cm. </div>展开更多
The geopolitical construct of the Indo-Pacific has evolved as one of the most important ones of the twenty-first century and more particularly of the last decade.While there is little or no consensus on where the Indo...The geopolitical construct of the Indo-Pacific has evolved as one of the most important ones of the twenty-first century and more particularly of the last decade.While there is little or no consensus on where the Indo-Pacific Region(IPR)begins or ends,it has inadvertently become a space where new convergences,competitions and alignments have emerged.These developments are intrinsically linked with the ascent of China as a global power,the retreat of the American strategic footprint and the emergence of a multi-polar world order.Within the larger Indo-Pacific construct,the Western Indian Ocean region is a space of considerable geopolitical and maritime interactions between states.The United Arab Emirates(UAE)and India are both countries of the Western Indian Ocean region while France is a resident power of the region owing to the presence of two of its overseas departments-Mayotte and Reunion—and its inter services bases in the UAE and Djibouti.The three countries have considerable experience in operationalising bilateral as well as trilateral initiatives.The lack of such initiatives in the Western Indian Ocean region could therefore offer the opportunity for UAE,India and France to come together in a trilateral arrangement to further their strategic interests and uphold the concept of a‘free and open Indo-Pacific’.The paper seeks to explore whether a trilateral partnership between the UAE,India and France could contribute to furthering their respective strategic autonomy in the Indo-Pacific Region.The paper will also endeavour to examine the conflicts and differences that could be expected and the possible areas of convergence.展开更多
Germany has gradually increased its investment in Africa.In addition to promoting traditional economic and trade cooperation,Germany has paid more attention to security issues in Africa and to improved cooperation in ...Germany has gradually increased its investment in Africa.In addition to promoting traditional economic and trade cooperation,Germany has paid more attention to security issues in Africa and to improved cooperation in defense,immigration and counter-terrorism.As Germany explores new models of development aid and encourages renewable energy and environmental protection in African countries,German capability and willingness to cooperate with African nations are on the rise.While Germany welcomes the African consumer market,historic problems centering on value differences and the European Union’s diplomatic constraints obstruct German-African cooperation over the short term.Germany promotes trilateral cooperation with China and Africa but encounters several challenges within its forward momentum.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
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
文摘<div style="text-align:justify;"> Aiming at the problems of LED-based visible light positioning system such as unstable illumination, Lambertian model transmission limitation, large positioning error, etc., it is proposed to use PWM to drive the LED, use the curve fitting method to obtain the ranging model, and estimate the target position according to the trilateral algorithm. A positioning system platform based on the microcontroller MiniSTM32 was built to test the performance of the transceiver circuit. The experimental results showed that the positioning error of less than 3 cm was achieved in a space of 80 cm × 80 cm × 80 cm. </div>
文摘The geopolitical construct of the Indo-Pacific has evolved as one of the most important ones of the twenty-first century and more particularly of the last decade.While there is little or no consensus on where the Indo-Pacific Region(IPR)begins or ends,it has inadvertently become a space where new convergences,competitions and alignments have emerged.These developments are intrinsically linked with the ascent of China as a global power,the retreat of the American strategic footprint and the emergence of a multi-polar world order.Within the larger Indo-Pacific construct,the Western Indian Ocean region is a space of considerable geopolitical and maritime interactions between states.The United Arab Emirates(UAE)and India are both countries of the Western Indian Ocean region while France is a resident power of the region owing to the presence of two of its overseas departments-Mayotte and Reunion—and its inter services bases in the UAE and Djibouti.The three countries have considerable experience in operationalising bilateral as well as trilateral initiatives.The lack of such initiatives in the Western Indian Ocean region could therefore offer the opportunity for UAE,India and France to come together in a trilateral arrangement to further their strategic interests and uphold the concept of a‘free and open Indo-Pacific’.The paper seeks to explore whether a trilateral partnership between the UAE,India and France could contribute to furthering their respective strategic autonomy in the Indo-Pacific Region.The paper will also endeavour to examine the conflicts and differences that could be expected and the possible areas of convergence.
文摘Germany has gradually increased its investment in Africa.In addition to promoting traditional economic and trade cooperation,Germany has paid more attention to security issues in Africa and to improved cooperation in defense,immigration and counter-terrorism.As Germany explores new models of development aid and encourages renewable energy and environmental protection in African countries,German capability and willingness to cooperate with African nations are on the rise.While Germany welcomes the African consumer market,historic problems centering on value differences and the European Union’s diplomatic constraints obstruct German-African cooperation over the short term.Germany promotes trilateral cooperation with China and Africa but encounters several challenges within its forward momentum.
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.
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.
文摘利用高光谱遥感技术定量估测野鸭湖湿地植被含水量,对于监测和诊断野鸭湖湿地植被的生理状况及生长趋势具有重要意义,也能够为高光谱遥感影像在野鸭湖湿地植被含水量诊断中的实际应用提供理论依据和技术支持。采用Field Spec 3野外高光谱辐射仪,获取了野鸭湖典型湿地植被冠层和叶片的光谱,并测定了对应的含水量。以上述实测数据为基础,首先以芦苇为例初步探明了不同含水量水平下典型湿地植被冠层和叶片光谱反射率的响应模式,然后采用相关性及单变量线性与非线性拟合分析技术,从冠层和叶片两种层次,对不同尺度下的含水量与"三边"参数及高光谱植被指数进行了分析拟合,并采用交叉检验中的3K-CV方法对估算模型进行了测试和检验,确立了不同尺度下野鸭湖湿地植被含水量的定量监测模型。结果表明:(1)随着含水量水平的增加,芦苇冠层与叶片光谱在可见光波段(350—760 nm)和红外波段(760—2500 nm)的反射率均呈逐渐降低趋势。(2)不同尺度含水量与选取的光谱特征参数整体上相关性较强,与"三边"参数基本上都呈极显著相关,相关系数最大达到0.906;与高光谱指数全部呈极显著相关,相关系数最小为0.455,最大达到0.919,并通过选取不同尺度上相关性最佳的光谱特征参数,分别基于"三边"参数和高光谱植被指数构建了不同尺度下的含水量估算模型。其中,冠层尺度下,黄边面积(SDy)与SRWI(Simple Ratio Water Index)的估算效果最好,估算模型分别为y=-9.462x2-2.671x+0.608和y=0.219e1.010x;叶片尺度下,红边面积(SDr)与WI(Water Index)的估算效果最好,估算模型分别为y=0.562x+0.376和y=2.028x2-0.476x-1.009。通过3K-CV的交叉验证,不同尺度下的含水量估算模型均取得了较为理想的预测精度,预测精度的最小值为94.92%,最大值为97.06%,表明估测模型具有较高的可靠性与普适性。(3)高光谱植被指�
