As the competition for marine resources is increasingly fierce,the security of underwater acoustic communication has attracted a great deal of attention.The information and location of the communicating platform can b...As the competition for marine resources is increasingly fierce,the security of underwater acoustic communication has attracted a great deal of attention.The information and location of the communicating platform can be leaked during the traditional underwater acoustic communication technology.According to the unique advantages of chaos communication,we put forward a novel communication scheme using complex parameter modulation and the complex Lorenz system.Firstly,we design a feedback controller and parameter update laws in a complex-variable form with rigorous mathematical proofs(while many previous references on the real-variable form were only special cases in which the imaginary part was zero),which can be realized in practical engineering;then we design a new communication scheme employing parameter modulation.The main parameter spaces of the complex Lorenz system are discussed,then they are adopted in our communication scheme.We also find that there exist parametric attractors in the complex Lorenz system.We make numerical simulations in two channels for digital signals and the simulations verify our conclusions.展开更多
Parameter optimization integrating operation parameters and structure parameters for the purpose of high permeate flux,high productivity and low exergy consumption of direct contact membrane distillation (DCMD) proces...Parameter optimization integrating operation parameters and structure parameters for the purpose of high permeate flux,high productivity and low exergy consumption of direct contact membrane distillation (DCMD) process was conducted based on Taguchi experimental design. L16(45) orthogonal experiments were carried out with feed inlet temperature,permeate stream inlet temperature,flow rate,module packing density and length-diameter ratio as optimization parameters and with permeate flux,water productivity per unit volume of module and water production per unit exergy loss separately as optimization objectives. By using range analysis method,the dominance degree of the various influencing factors for the three objectives was analyzed and the optimum condition was obtained for the three objectives separately. Furthermore,the multi-objectives optimization was performed based on a weight grade method. The combined optimum conditions are feed inlet temperature 75℃,packing density 30% ,length-diameter ratio 10,permeate stream inlet temperature 30 ℃ and flow rate 25 L/h,which is in order of their dominance degree,and the validity of the optimization scheme was confirmed.展开更多
Primary frequency regulation is one of the important regulation means to maintain the stable operation of the power grid, and for a single unit, especially the nuclear power unit, the frequency regulation process is a...Primary frequency regulation is one of the important regulation means to maintain the stable operation of the power grid, and for a single unit, especially the nuclear power unit, the frequency regulation process is an unstable factor. With the increasing capacity of nuclear motor assembly machine, it is bound to shoulder the heavy responsibility of peak shaving and frequency modulation. However, its own particularity determines that it cannot be as flexible as thermal power plants and other power plants in terms of frequency modulation, and it is necessary to find a balance between maintaining the stability of the power grid and the safe and stable operation of units. Taking 650MW nuclear power steam turbine unit as an example, this paper introduces and analyzes in detail the control principle, control process, frequency modulation parameter setting of its primary frequency modulation, as well as the adverse effects of reactor protection actions such as reactor over power that may be caused by transient events and primary frequency modulation process. By taking technical measures such as adjusting the mode of primary frequency modulation operation, we can reduce the impact of external network faults on the unit, summarize the experience of transient disposal, and improve the plan, improve the ability of the main control operator to judge and deal with the transient, so as to ensure that the unit can meet the requirements of the primary frequency modulation response of the power grid on the basis of safe and stable operation.展开更多
The autonomic nervous system(ANS),mainly composed of the sympathetic nerve and the parasympathetic nerve,plays an important role in maintaining the homeostasis of the body's internal milieu.The vagus nerve,as an i...The autonomic nervous system(ANS),mainly composed of the sympathetic nerve and the parasympathetic nerve,plays an important role in maintaining the homeostasis of the body's internal milieu.The vagus nerve,as an integral component of the parasympathetic nervous system,functions in an antagonistic manner with the sympathetic nervous system to modulate crucial physiological parameters such as the human heart rate,respiratory rate,glandular secretory activities,and the distribution of blood flow within vital organs including the liver and adrenal glands.(1)Through the modulation of ANS,acupuncture has demonstrated its potential utility in the treatment of a diverse range of related disorders,which include gastrointestinal motility dysfunctions,cardiovascular pathologies,conditions responsive to anti-inflammatory interventions,and anxiety-related disorders.展开更多
A scheme of chaotic secure communication based on the parameter modulation and the inversion of a chaotic dynamical system is analyzed. According to this scheme, information signal is modulated by a bifurcation parame...A scheme of chaotic secure communication based on the parameter modulation and the inversion of a chaotic dynamical system is analyzed. According to this scheme, information signal is modulated by a bifurcation parameter of the transmitter, which is in chaotic state. In the receiver, a proportional integral feedback demodulator is used to demodulate the information signal, which only uses the available synchronizing error as well as stateness of receiver. The purpose of this demodulator is proposed to overcome the influence of differentiation operation, nonlinear part and singularities in chaotic system. Numerical simulation is proposed to show the effectiveness of this demodulator.展开更多
Photovoltaic(PV)system’s performance is significantly affected by its orientation and tilt angle.Experimental investigation(indoor and outdoor)has been carried out to trace the variation in PV performance and electri...Photovoltaic(PV)system’s performance is significantly affected by its orientation and tilt angle.Experimental investigation(indoor and outdoor)has been carried out to trace the variation in PV performance and electrical parameters at varying tilt angles in Malaysian conditions.There were two experimental modus:1)varying module tilt under constant irradiation level,2)varying irradiation intensity at the optimum tilt set up.For the former scheme,the irradiation level was maintained at 750 W/m^(2),and for the later arrangement,the module tilt angle was varied from 0 o to 80 o by means of a single-axis tracker.Results show that under constant irradiation of 750 W/m^(2),every 5 o increase in tilt angle causes a power drop of 2.09 W at indoor and 3.45 W at outdoor.In contrast,for the same condition,efficiency decreases by 0.54%for indoor case and by 0.76%at outdoor.On the other hand,for every 100 W/m^(2)increase in irradiation,solar cell temperature rises by 7.52℃at indoor and by 5.67℃at outdoor.As of module electrical parameters,open-circuit voltage,short-circuit current,maximum power point voltage and maximum power point current drops substantially with increasing tilt angle,whereas fill factor drops rather gradually.Outdoor experimental investigation confirms that the optimum tilt angle at Malaysian conditions is 15 o and orienting a PV module this angle will maximize the sun’s energy captured and thereby enhance its performance.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.U1806202,61773010,and 61903207)the International Collaborative Research Project of Qilu University of Technology(Grant No.QLUTGJHZ2018020)Major Scientific and Technological Innovation Projects of Shandong Province,China(Grant Nos.2019JZZY010731 and 2020CXGC010901).
文摘As the competition for marine resources is increasingly fierce,the security of underwater acoustic communication has attracted a great deal of attention.The information and location of the communicating platform can be leaked during the traditional underwater acoustic communication technology.According to the unique advantages of chaos communication,we put forward a novel communication scheme using complex parameter modulation and the complex Lorenz system.Firstly,we design a feedback controller and parameter update laws in a complex-variable form with rigorous mathematical proofs(while many previous references on the real-variable form were only special cases in which the imaginary part was zero),which can be realized in practical engineering;then we design a new communication scheme employing parameter modulation.The main parameter spaces of the complex Lorenz system are discussed,then they are adopted in our communication scheme.We also find that there exist parametric attractors in the complex Lorenz system.We make numerical simulations in two channels for digital signals and the simulations verify our conclusions.
文摘Parameter optimization integrating operation parameters and structure parameters for the purpose of high permeate flux,high productivity and low exergy consumption of direct contact membrane distillation (DCMD) process was conducted based on Taguchi experimental design. L16(45) orthogonal experiments were carried out with feed inlet temperature,permeate stream inlet temperature,flow rate,module packing density and length-diameter ratio as optimization parameters and with permeate flux,water productivity per unit volume of module and water production per unit exergy loss separately as optimization objectives. By using range analysis method,the dominance degree of the various influencing factors for the three objectives was analyzed and the optimum condition was obtained for the three objectives separately. Furthermore,the multi-objectives optimization was performed based on a weight grade method. The combined optimum conditions are feed inlet temperature 75℃,packing density 30% ,length-diameter ratio 10,permeate stream inlet temperature 30 ℃ and flow rate 25 L/h,which is in order of their dominance degree,and the validity of the optimization scheme was confirmed.
文摘Primary frequency regulation is one of the important regulation means to maintain the stable operation of the power grid, and for a single unit, especially the nuclear power unit, the frequency regulation process is an unstable factor. With the increasing capacity of nuclear motor assembly machine, it is bound to shoulder the heavy responsibility of peak shaving and frequency modulation. However, its own particularity determines that it cannot be as flexible as thermal power plants and other power plants in terms of frequency modulation, and it is necessary to find a balance between maintaining the stability of the power grid and the safe and stable operation of units. Taking 650MW nuclear power steam turbine unit as an example, this paper introduces and analyzes in detail the control principle, control process, frequency modulation parameter setting of its primary frequency modulation, as well as the adverse effects of reactor protection actions such as reactor over power that may be caused by transient events and primary frequency modulation process. By taking technical measures such as adjusting the mode of primary frequency modulation operation, we can reduce the impact of external network faults on the unit, summarize the experience of transient disposal, and improve the plan, improve the ability of the main control operator to judge and deal with the transient, so as to ensure that the unit can meet the requirements of the primary frequency modulation response of the power grid on the basis of safe and stable operation.
基金Supported by the National Key Research and Development Program(No.2022YFC3500704)。
文摘The autonomic nervous system(ANS),mainly composed of the sympathetic nerve and the parasympathetic nerve,plays an important role in maintaining the homeostasis of the body's internal milieu.The vagus nerve,as an integral component of the parasympathetic nervous system,functions in an antagonistic manner with the sympathetic nervous system to modulate crucial physiological parameters such as the human heart rate,respiratory rate,glandular secretory activities,and the distribution of blood flow within vital organs including the liver and adrenal glands.(1)Through the modulation of ANS,acupuncture has demonstrated its potential utility in the treatment of a diverse range of related disorders,which include gastrointestinal motility dysfunctions,cardiovascular pathologies,conditions responsive to anti-inflammatory interventions,and anxiety-related disorders.
文摘A scheme of chaotic secure communication based on the parameter modulation and the inversion of a chaotic dynamical system is analyzed. According to this scheme, information signal is modulated by a bifurcation parameter of the transmitter, which is in chaotic state. In the receiver, a proportional integral feedback demodulator is used to demodulate the information signal, which only uses the available synchronizing error as well as stateness of receiver. The purpose of this demodulator is proposed to overcome the influence of differentiation operation, nonlinear part and singularities in chaotic system. Numerical simulation is proposed to show the effectiveness of this demodulator.
基金The authors would like to acknowledge the financial support from University of Malaya,Impact Oriented Interdisciplinary Research Grant(Project:IIRG015B-2019)to carry out this research.
文摘Photovoltaic(PV)system’s performance is significantly affected by its orientation and tilt angle.Experimental investigation(indoor and outdoor)has been carried out to trace the variation in PV performance and electrical parameters at varying tilt angles in Malaysian conditions.There were two experimental modus:1)varying module tilt under constant irradiation level,2)varying irradiation intensity at the optimum tilt set up.For the former scheme,the irradiation level was maintained at 750 W/m^(2),and for the later arrangement,the module tilt angle was varied from 0 o to 80 o by means of a single-axis tracker.Results show that under constant irradiation of 750 W/m^(2),every 5 o increase in tilt angle causes a power drop of 2.09 W at indoor and 3.45 W at outdoor.In contrast,for the same condition,efficiency decreases by 0.54%for indoor case and by 0.76%at outdoor.On the other hand,for every 100 W/m^(2)increase in irradiation,solar cell temperature rises by 7.52℃at indoor and by 5.67℃at outdoor.As of module electrical parameters,open-circuit voltage,short-circuit current,maximum power point voltage and maximum power point current drops substantially with increasing tilt angle,whereas fill factor drops rather gradually.Outdoor experimental investigation confirms that the optimum tilt angle at Malaysian conditions is 15 o and orienting a PV module this angle will maximize the sun’s energy captured and thereby enhance its performance.
