Transient analysis of 33 KV power transmission line stability of Egi communi-ty is considered in this research work with the aim of reducing the frequency of fault occurrence and voltage collapse in the network. The s...Transient analysis of 33 KV power transmission line stability of Egi communi-ty is considered in this research work with the aim of reducing the frequency of fault occurrence and voltage collapse in the network. The supply is taken from Egi generating station located at Total Nigeria Limited Gas Plant Obite at voltage level of 33 KV to Egi communities. This work focuses on the transient nature of network stability since transient fault is the most dangerous in elec-trical systems. The swinging of the generator rotor in the event of transient three-phase short circuit fault can be monitored by the circuit breakers and the protective relays which causes mal-functioning of the circuit breakers and pro-tective relays leading to abnormal behavior of the network. Therefore, data obtained from the power station were used as a case study of Independent Power Producer (IPP) in Nigeria. For investigation of the power angle, angular velocity, rotor angle differential changes, and angular velocity differential changes, an electrical transient analyzer tool was employed (ETap version 16.00) for circuit breaker and protective relay time setting of (0.00, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60). The work used the Trapezoidal numerical technique for data analysis. The graphs were plotted using Matlab R2015a and the results obtained showed that when a symmetrical three-phase short circuit fault occur at one or any of the feeders, the fault must be cleared as quick as possible through the coordination of the circuit breakers and protective relays. For this research work, 17 cycles corresponding to relay time setting of t = 0.34 s were recommended and at each cycle, changes in time with respect to changes in rotor angle, angular velocity, rotor differential and angular velocity differential were calculated on the power network simultaneously. The results demonstrated that the Trapezoidal method is numerically stable, accurate and has faster respond time when compared to Modified Euler and swing equat展开更多
Global navigation satellite system(GNSS)carrier phase observations are two orders of higher accuracy than pseudo-range observations,and they are less affected by multipath besides.As a result,the time transfer accurac...Global navigation satellite system(GNSS)carrier phase observations are two orders of higher accuracy than pseudo-range observations,and they are less affected by multipath besides.As a result,the time transfer accuracy can reach 0.1 ns,and the frequency transfer stability can reach 1×10^-15 with carrier phase(CP)method,therefore CP method is considered the most accurate and promising time transfer technology.The focus of this paper is to present a comprehensive summary of CP method,with specific attention directed toward day-boundary clock jump,ambiguity resolution(AR),multi-system time transfer and real-time time transfer.Day-boundary clock jump is essentially caused by pseudo-range noise.Several approaches were proposed to solve the problem,such as continuously processing strategy,sliding batch and bidirectional filtering methods which were compared in this study.Additionally,researches on AR in CP method were introduced.Many scholars attempted to fix the single-difference ambiguities to improve the time transfer result,however,owing to the uncalibrated phase delay(UPD)was not considered,the current studies on AR in CP method were still immature.Moreover,because four GNSS systems could be used for time-transfer currently,which was helpful to increase the accuracy and reliability,the researches on multi-system time transfer were reviewed.What’s more,real-time time transfer attracted more attention nowadays,the preliminary research results were presented.展开更多
In this paper, a new complex variable defined as “precursive time” able to correlate general relativity (GR) and quantum field theory (QFT) in a single principle was characterized. The thesis was elaborated accordin...In this paper, a new complex variable defined as “precursive time” able to correlate general relativity (GR) and quantum field theory (QFT) in a single principle was characterized. The thesis was elaborated according to a hypothesis coherent with the “Einstein’s General Theory of Relativity”, making use of a new mathematical-topological variety called “time-space” developed on the properties of the hypersphere and explained mathematically through the quaternion of Hurwitz-Lipschitz algebra. In this publication we pay attention to the interaction between the weak nuclear force theory (EWT) and the nuclear mass of the Standard Model.展开更多
This paper investigates the problem of event-triggered finite-time <i>H</i><sub>∞</sub> control for a class of switched stochastic systems. The main objective of this study is to design an eve...This paper investigates the problem of event-triggered finite-time <i>H</i><sub>∞</sub> control for a class of switched stochastic systems. The main objective of this study is to design an event-triggered state feedback <i>H</i><sub>∞</sub> controller such that the resulting closed-loop system is finite-time bounded and satisfies a prescribed <i>H</i><sub>∞</sub> level in some given finite-time interval. Based on stochastic differential equations theory and average dwell time approach, sufficient conditions are derived to ensure the finite-time stochastic stability with the prescribed <i>H</i><sub>∞</sub> performance for the relevant closed-loop system by employing the linear matrix inequality technique. Finally, the desired state feedback <i>H</i><sub>∞</sub> controller gain matrices can be expressed in an explicit form.展开更多
In the relativistic mechanics, we calculate a minimal distance between the time scale of a one-dimensional motion having a larger velocity and the time scale of a similar motion with a lower velocity. Concerning the q...In the relativistic mechanics, we calculate a minimal distance between the time scale of a one-dimensional motion having a larger velocity and the time scale of a similar motion with a lower velocity. Concerning the quantum theory, we demonstrate that mechanical parameters entering the electron motion in the Bohr hydrogen atom can provide us with a correct size of the time interval entering the Joule-Lenz law for the emission energy between two neighbouring quantum levels of the atom.展开更多
This work is devoted to an experimental study of metallic pressure cooker insulated with kapok wool, a vegetal biodegradable fiber. Experiments conducted on the cooling of hot water in the equipment revealed very low ...This work is devoted to an experimental study of metallic pressure cooker insulated with kapok wool, a vegetal biodegradable fiber. Experiments conducted on the cooling of hot water in the equipment revealed very low heat losses and a time constant of 60 hours on average. As a result, the equipment makes it possible to finish cooking meals only thanks to the heat stored at the beginning of cooking and keeps cooked dishes warm for long hours. The thermal phase shift of the pressure cooker is around 7?h. Cooking tests conducted on some local dishes revealed about 70% butane gas savings for cooking cowpea and white rice, 38% for cooking fatty rice, 75% for pasta and couscous, and 30% for cooking potato stew. These results show that this technology can contribute to minimizing?energy consumption in the restaurant sector.展开更多
The first necessary condition for the onset of an earthquake is the penetration of explosive gas into an explosive zone as a result of physical or chemical reaction. The second necessary condition is to ensure the sub...The first necessary condition for the onset of an earthquake is the penetration of explosive gas into an explosive zone as a result of physical or chemical reaction. The second necessary condition is to ensure the subsequent propagation of the flame after ignition. The latter condition has made it possible to explain the impact of a cyclone on the emergence of 42 strongest earthquakes in the 21st century. If violation of this condition can be achieved with the help of vibrators or explosions, this will result in a decrease in the magnitude of an earthquake or even a complete prevention of earthquakes. Thus, the second condition is essentially a “pressure lock” that opens (with a decrease in the pressure caused by a cyclone), which leads to an earthquake or closes (with an increase in the pressure caused by an anticyclone or human interference using vibrators or explosions), which leads to earthquake prevention. Kinetic equations of the 2nd type were used to describe chemical reactions and obtain formulas for the precursor time, which made it possible to describe earthquakes of the chemical channel. The set of experimental time values of the earthquake precursor described by the physical model includes about 20% of all earthquakes;80% of earthquakes can be attributed to the chemical channel for earthquakes that occurred in Dushanbe in 1983. All earthquakes in Tiberias in June 2018 passed through the chemical channel, which can be concluded from the small magnitude of these earthquakes. Several proposals have been made, including: 1) creating a new sensor for the geochemical method, which allows determining the epicenter of a future earthquake;2) creating a network of stations with a new sensor for determining the epicenter and an atmospheric pressure meter installed at each station (this will determine if the “pressure lock” is closed by an anticyclone, which can lead to a decrease in the magnitude of an earthquake or even prevent an earthquake);3) installing vibrators in epicenters (or making daily explos展开更多
In recent years, power generation using renewable energy sources has been developed as a solution to the global warming problem. Among these power generation methods, wind power generation is increasing. However, as t...In recent years, power generation using renewable energy sources has been developed as a solution to the global warming problem. Among these power generation methods, wind power generation is increasing. However, as the penetration level of wind power generation increases, the low inertia and lack of synchronous power characteristics of the penetrated power system can have a significant impact on the transient stability of the grid. The virtual synchronous generator provides the ability of virtual inertia and synchronous power to interconnected inverters. The interconnected inverter with the virtual synchronous generator ability uses, in general, PI control based current controller. This paper proposes a new current-control method and compares it with conventional methods. The proposed current control is a method that follows virtual synchronous generator model that changes every moment by solving the discrete-time linear quadratic optimal control problem for each sampling time interval. The new method follows the conventional method, and therefore the reactive power fluctuation can be suppressed and the interconnected inverter will be downsized.展开更多
Up to the present time gravitational-wave detectors, such as LIGO and Virgo, have been sensitive to frequencies on the order of a few thousand to a small fraction of an Hz. They have been most effective in the study o...Up to the present time gravitational-wave detectors, such as LIGO and Virgo, have been sensitive to frequencies on the order of a few thousand to a small fraction of an Hz. They have been most effective in the study of black-hole mergers. We suggest that high-frequency relic gravitational wave (HFRGW) detectors be developed, especially the Li-Baker HFRGW detector, in the gigahertz and higher frequency range. We believe collecting cosmological, primordial observational data especially generated during the first few seconds after the beginning of our Universe is extremely important. One motivation for this paper is, therefore, that we are confident that observation of relic gravitational waves will provide vital information about the birth of our Universe and its early dynamical evolution. Other astrophysical applications of HFRGW detectors involve the entropy growth of the early Universe, an ability to study alternatives to inflation and to provide clues about the symmetries underlying new physics at the highest energies. A working hypothesis or theory, based upon the rollout of our Universe from infinitesimal Planck Length and Planck Time is presented. This theory involves the rapid motion of time and matter during that early time having frequencies on the order of trillions of cycles per second or more. Several alternative HFRGW detectors are described and the proposed Li-Baker HFRGW detector, which is theoretically sensitive to GW amplitudes, A, as small as 10-32, is discussed in detail. Such sensitivity may provide a means for verifying or falsifying the rollout of our Universe working hypothesis. Essentially a combination of theory and experimentation is presented. It is recommended that plans and detailed specifications for the Li-Baker HFRGW detector be prepared in order to expedite its fabrication.展开更多
In the first step, the Ehrenfest reasoning concerning the adiabatic invariance of the angular orbital momentum is applied to the electron motion in the hydrogen atom. It is demonstrated that the time of the energy emi...In the first step, the Ehrenfest reasoning concerning the adiabatic invariance of the angular orbital momentum is applied to the electron motion in the hydrogen atom. It is demonstrated that the time of the energy emission from the quantum level n+1 to level n can be deduced from the orbital angular momentum examined in the hydrogen atom. This time is found precisely equal to the time interval dictated by the Joule-Lenz law governing the electron transition between the levels n+1 and n. In the next step, the mechanical parameters entering the quantum systems are applied in calculating the time intervals characteristic for the electron transitions. This concerns the neighbouring energy levels in the hydrogen atom as well as the Landau levels in the electron gas submitted to the action of a constant magnetic field.展开更多
Solid-state nanopore DNA sequencing modified method is developed. Method is based on the tunnel current investigation through the nanogap made on lateral gold electrodes in the form of nanowires or nanoribbons. The mo...Solid-state nanopore DNA sequencing modified method is developed. Method is based on the tunnel current investigation through the nanogap made on lateral gold electrodes in the form of nanowires or nanoribbons. The movement of DNA in aqueous solution is regulated by the potential applied to reference electrode. The potential applied to the lateral metal electrodes helps to the creation of the molecular junctions. They consist of the nucleosides passing through the pores. Taking into account that DNA moves under gravity, electrophoretic and drag forces, the analytic expression for the DNA translocation speed is calculated and analyzed. The conditions for decreasing the DNA translocation speed or increasing the nucleosides reading time are received. It is shown that one can control value of the DNA molecules bases reading time and the frequency of the bases passes by the choice of magnitude of the potential applied to reference electrode. Our results, therefore potentially suggest a realistic, inherently design-specific, high-throughput nanopore DNA sequencing device/cell as a de-novo alternative to the existing methods.展开更多
In order to promote the efficiency of teachers’teaching and students’learning,based on the naturalistic inquiry,the study mainly describes the typical features of teacher talk.High quality language input rely on the...In order to promote the efficiency of teachers’teaching and students’learning,based on the naturalistic inquiry,the study mainly describes the typical features of teacher talk.High quality language input rely on the teaching materials and curricu⁃lum design,more importantly,it relies on the teacher talk to express and explain language knowledge.The teacher talk has an influ⁃ence on learners’learning attitude,classroom performance and the learning process.If used appropriately,the teacher talk can pro⁃mote the communication as well as inspire students to participate the classroom interaction.展开更多
The study was conducted to evaluate the effect of baking conditions of partially-dried potato slices (PDPS) prior baking on the quality attributes of the resultant baked potato chips. Baking experiment was conducted a...The study was conducted to evaluate the effect of baking conditions of partially-dried potato slices (PDPS) prior baking on the quality attributes of the resultant baked potato chips. Baking experiment was conducted at power levels of 80 and 100 Watts for different baking times according to microwave power used. Texture, color measurements and sensory evaluation were carried out on resultant baked potato chips. The results showed that partially drying step (even to 40% moisture content) prior microwave baking resulted in marked crispiness as well as brilliant yellow in resultant potato chips. The optimum conditions for the best quality of partially-dried potato chips were microwave cooking at power level of 100 Watts for 100 seconds.展开更多
Background: A Randomized Controlled Trial (RCT) has been elaborated where goal directed fluid and hemodynamic therapy (GDFHT) will be realized with trans-thoracic echocardiographic aortic blood flow peak velocity vari...Background: A Randomized Controlled Trial (RCT) has been elaborated where goal directed fluid and hemodynamic therapy (GDFHT) will be realized with trans-thoracic echocardiographic aortic blood flow peak velocity variation (ΔVpeak) and distance minute (DM) to guide fluid therapy and hemodynamics in high risk pediatric surgical patients. This RCT will clarify the impact of GDFHT with ΔVpeak and DM on postoperative outcome in terms of morbidity, length of stay in the intensive care unit (LOSICU), length of mechanical ventilation (LMV) and length of hospital stay (LOS) in children. To determine values of ΔVpeak, DM and VTI predictive of these postoperative outcomes, an observational pilot study will be realized. This pilot study is described here. The primary objective of this study is to determine values of ΔVpeak, DM and ITV predictive of postoperative outcome in children in terms of morbidity. The secondary objectives are to determine values of ΔVpeak, DM and ITV predictive of LOSICU, LMV, LOS, intraoperative, postoperative fluid administration and vasoactive-inotropic therapy. Methods: 500 - 1000 children aged less than 18 years will be included prospectively. Statistic analysis will be realized with XLSTAT 2019.4.2 software or plus. Results and Conclusions: This trial protocol will determine values of ΔVpeak, DM and ITV with echocardiography predictive of postoperative outcome in children.展开更多
Research into the impact of road accidents on drivers is essential to effective post-crash interventions.However,due to limited data and resources,the current research focus is mainly on those who have suffered severe...Research into the impact of road accidents on drivers is essential to effective post-crash interventions.However,due to limited data and resources,the current research focus is mainly on those who have suffered severe injuries.In this paper,we propose a novel approach to examining the impact that being involved in a crash has on drivers by using traffic surveillance data.In traffic video surveillance systems,the locations of vehicles at different moments in time are captured and their headway,which is an important indicator of driving behavior,can be calculated from this information.It was found that there was a sudden increase in headway when drivers return to the road after being involved in a crash,but that the headway returned to its pre-crash level over time.We further analyzed the duration of the decay using a Cox proportional hazards regression model,which revealed many significant factors(related to the driver,vehicle,and nature of the accident)behind the survival time of the increased headway.Our approach is able to reveal the crash impact on drivers in a convenient and economical way.It can enhance the understanding of the impact of a crash on drivers,and help to devise more effective re-education programs and other interventions to encourage drivers who are involved in crashes to drive more safely in the future.展开更多
In the modern era of manufacturing, it is important to optimize every design parameter in product development stage to reduce cost, material usage and to achieve the desired efficacy level. There are various models wh...In the modern era of manufacturing, it is important to optimize every design parameter in product development stage to reduce cost, material usage and to achieve the desired efficacy level. There are various models which serve those purposes, for instance, Design of Experiment (DoE) is used to check the parameters after adopting optimization tactics which results in reduced cost or saving operating time. In this regard, this research aims to construct a DoE model on a portable workstation to optimize its design parameters. The methodology of DOE would be a 2 level 3 factors full factorial DOE which is conducted to determine the optimal value for three design parameters (factors) which are material density, the length of the table and the length of the table stand in terms of the response which is the required time of fold ability function of the portable workstation. Based upon the evaluated interactions between the parameters, the optimized parameters are chosen for responses. Here, the resultant design parameters are at their lowest level, so the goal of time efficiency in fold ability function is achieved. This similar sort of DoE can be implemented in the furniture and other manufacturing industries who wish to optimize their material usage as well as increase efficiency and reduce cycle time.展开更多
文摘Transient analysis of 33 KV power transmission line stability of Egi communi-ty is considered in this research work with the aim of reducing the frequency of fault occurrence and voltage collapse in the network. The supply is taken from Egi generating station located at Total Nigeria Limited Gas Plant Obite at voltage level of 33 KV to Egi communities. This work focuses on the transient nature of network stability since transient fault is the most dangerous in elec-trical systems. The swinging of the generator rotor in the event of transient three-phase short circuit fault can be monitored by the circuit breakers and the protective relays which causes mal-functioning of the circuit breakers and pro-tective relays leading to abnormal behavior of the network. Therefore, data obtained from the power station were used as a case study of Independent Power Producer (IPP) in Nigeria. For investigation of the power angle, angular velocity, rotor angle differential changes, and angular velocity differential changes, an electrical transient analyzer tool was employed (ETap version 16.00) for circuit breaker and protective relay time setting of (0.00, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60). The work used the Trapezoidal numerical technique for data analysis. The graphs were plotted using Matlab R2015a and the results obtained showed that when a symmetrical three-phase short circuit fault occur at one or any of the feeders, the fault must be cleared as quick as possible through the coordination of the circuit breakers and protective relays. For this research work, 17 cycles corresponding to relay time setting of t = 0.34 s were recommended and at each cycle, changes in time with respect to changes in rotor angle, angular velocity, rotor differential and angular velocity differential were calculated on the power network simultaneously. The results demonstrated that the Trapezoidal method is numerically stable, accurate and has faster respond time when compared to Modified Euler and swing equat
基金supported in part by the National Key Research and Development Program of China(Grant No.2016YFB0800401)in part by the National Natural Science Foundation of China(Grants Nos.61621003,61532020&11472290)。
文摘Global navigation satellite system(GNSS)carrier phase observations are two orders of higher accuracy than pseudo-range observations,and they are less affected by multipath besides.As a result,the time transfer accuracy can reach 0.1 ns,and the frequency transfer stability can reach 1×10^-15 with carrier phase(CP)method,therefore CP method is considered the most accurate and promising time transfer technology.The focus of this paper is to present a comprehensive summary of CP method,with specific attention directed toward day-boundary clock jump,ambiguity resolution(AR),multi-system time transfer and real-time time transfer.Day-boundary clock jump is essentially caused by pseudo-range noise.Several approaches were proposed to solve the problem,such as continuously processing strategy,sliding batch and bidirectional filtering methods which were compared in this study.Additionally,researches on AR in CP method were introduced.Many scholars attempted to fix the single-difference ambiguities to improve the time transfer result,however,owing to the uncalibrated phase delay(UPD)was not considered,the current studies on AR in CP method were still immature.Moreover,because four GNSS systems could be used for time-transfer currently,which was helpful to increase the accuracy and reliability,the researches on multi-system time transfer were reviewed.What’s more,real-time time transfer attracted more attention nowadays,the preliminary research results were presented.
文摘In this paper, a new complex variable defined as “precursive time” able to correlate general relativity (GR) and quantum field theory (QFT) in a single principle was characterized. The thesis was elaborated according to a hypothesis coherent with the “Einstein’s General Theory of Relativity”, making use of a new mathematical-topological variety called “time-space” developed on the properties of the hypersphere and explained mathematically through the quaternion of Hurwitz-Lipschitz algebra. In this publication we pay attention to the interaction between the weak nuclear force theory (EWT) and the nuclear mass of the Standard Model.
文摘This paper investigates the problem of event-triggered finite-time <i>H</i><sub>∞</sub> control for a class of switched stochastic systems. The main objective of this study is to design an event-triggered state feedback <i>H</i><sub>∞</sub> controller such that the resulting closed-loop system is finite-time bounded and satisfies a prescribed <i>H</i><sub>∞</sub> level in some given finite-time interval. Based on stochastic differential equations theory and average dwell time approach, sufficient conditions are derived to ensure the finite-time stochastic stability with the prescribed <i>H</i><sub>∞</sub> performance for the relevant closed-loop system by employing the linear matrix inequality technique. Finally, the desired state feedback <i>H</i><sub>∞</sub> controller gain matrices can be expressed in an explicit form.
文摘In the relativistic mechanics, we calculate a minimal distance between the time scale of a one-dimensional motion having a larger velocity and the time scale of a similar motion with a lower velocity. Concerning the quantum theory, we demonstrate that mechanical parameters entering the electron motion in the Bohr hydrogen atom can provide us with a correct size of the time interval entering the Joule-Lenz law for the emission energy between two neighbouring quantum levels of the atom.
文摘This work is devoted to an experimental study of metallic pressure cooker insulated with kapok wool, a vegetal biodegradable fiber. Experiments conducted on the cooling of hot water in the equipment revealed very low heat losses and a time constant of 60 hours on average. As a result, the equipment makes it possible to finish cooking meals only thanks to the heat stored at the beginning of cooking and keeps cooked dishes warm for long hours. The thermal phase shift of the pressure cooker is around 7?h. Cooking tests conducted on some local dishes revealed about 70% butane gas savings for cooking cowpea and white rice, 38% for cooking fatty rice, 75% for pasta and couscous, and 30% for cooking potato stew. These results show that this technology can contribute to minimizing?energy consumption in the restaurant sector.
文摘The first necessary condition for the onset of an earthquake is the penetration of explosive gas into an explosive zone as a result of physical or chemical reaction. The second necessary condition is to ensure the subsequent propagation of the flame after ignition. The latter condition has made it possible to explain the impact of a cyclone on the emergence of 42 strongest earthquakes in the 21st century. If violation of this condition can be achieved with the help of vibrators or explosions, this will result in a decrease in the magnitude of an earthquake or even a complete prevention of earthquakes. Thus, the second condition is essentially a “pressure lock” that opens (with a decrease in the pressure caused by a cyclone), which leads to an earthquake or closes (with an increase in the pressure caused by an anticyclone or human interference using vibrators or explosions), which leads to earthquake prevention. Kinetic equations of the 2nd type were used to describe chemical reactions and obtain formulas for the precursor time, which made it possible to describe earthquakes of the chemical channel. The set of experimental time values of the earthquake precursor described by the physical model includes about 20% of all earthquakes;80% of earthquakes can be attributed to the chemical channel for earthquakes that occurred in Dushanbe in 1983. All earthquakes in Tiberias in June 2018 passed through the chemical channel, which can be concluded from the small magnitude of these earthquakes. Several proposals have been made, including: 1) creating a new sensor for the geochemical method, which allows determining the epicenter of a future earthquake;2) creating a network of stations with a new sensor for determining the epicenter and an atmospheric pressure meter installed at each station (this will determine if the “pressure lock” is closed by an anticyclone, which can lead to a decrease in the magnitude of an earthquake or even prevent an earthquake);3) installing vibrators in epicenters (or making daily explos
文摘In recent years, power generation using renewable energy sources has been developed as a solution to the global warming problem. Among these power generation methods, wind power generation is increasing. However, as the penetration level of wind power generation increases, the low inertia and lack of synchronous power characteristics of the penetrated power system can have a significant impact on the transient stability of the grid. The virtual synchronous generator provides the ability of virtual inertia and synchronous power to interconnected inverters. The interconnected inverter with the virtual synchronous generator ability uses, in general, PI control based current controller. This paper proposes a new current-control method and compares it with conventional methods. The proposed current control is a method that follows virtual synchronous generator model that changes every moment by solving the discrete-time linear quadratic optimal control problem for each sampling time interval. The new method follows the conventional method, and therefore the reactive power fluctuation can be suppressed and the interconnected inverter will be downsized.
文摘Up to the present time gravitational-wave detectors, such as LIGO and Virgo, have been sensitive to frequencies on the order of a few thousand to a small fraction of an Hz. They have been most effective in the study of black-hole mergers. We suggest that high-frequency relic gravitational wave (HFRGW) detectors be developed, especially the Li-Baker HFRGW detector, in the gigahertz and higher frequency range. We believe collecting cosmological, primordial observational data especially generated during the first few seconds after the beginning of our Universe is extremely important. One motivation for this paper is, therefore, that we are confident that observation of relic gravitational waves will provide vital information about the birth of our Universe and its early dynamical evolution. Other astrophysical applications of HFRGW detectors involve the entropy growth of the early Universe, an ability to study alternatives to inflation and to provide clues about the symmetries underlying new physics at the highest energies. A working hypothesis or theory, based upon the rollout of our Universe from infinitesimal Planck Length and Planck Time is presented. This theory involves the rapid motion of time and matter during that early time having frequencies on the order of trillions of cycles per second or more. Several alternative HFRGW detectors are described and the proposed Li-Baker HFRGW detector, which is theoretically sensitive to GW amplitudes, A, as small as 10-32, is discussed in detail. Such sensitivity may provide a means for verifying or falsifying the rollout of our Universe working hypothesis. Essentially a combination of theory and experimentation is presented. It is recommended that plans and detailed specifications for the Li-Baker HFRGW detector be prepared in order to expedite its fabrication.
文摘In the first step, the Ehrenfest reasoning concerning the adiabatic invariance of the angular orbital momentum is applied to the electron motion in the hydrogen atom. It is demonstrated that the time of the energy emission from the quantum level n+1 to level n can be deduced from the orbital angular momentum examined in the hydrogen atom. This time is found precisely equal to the time interval dictated by the Joule-Lenz law governing the electron transition between the levels n+1 and n. In the next step, the mechanical parameters entering the quantum systems are applied in calculating the time intervals characteristic for the electron transitions. This concerns the neighbouring energy levels in the hydrogen atom as well as the Landau levels in the electron gas submitted to the action of a constant magnetic field.
文摘Solid-state nanopore DNA sequencing modified method is developed. Method is based on the tunnel current investigation through the nanogap made on lateral gold electrodes in the form of nanowires or nanoribbons. The movement of DNA in aqueous solution is regulated by the potential applied to reference electrode. The potential applied to the lateral metal electrodes helps to the creation of the molecular junctions. They consist of the nucleosides passing through the pores. Taking into account that DNA moves under gravity, electrophoretic and drag forces, the analytic expression for the DNA translocation speed is calculated and analyzed. The conditions for decreasing the DNA translocation speed or increasing the nucleosides reading time are received. It is shown that one can control value of the DNA molecules bases reading time and the frequency of the bases passes by the choice of magnitude of the potential applied to reference electrode. Our results, therefore potentially suggest a realistic, inherently design-specific, high-throughput nanopore DNA sequencing device/cell as a de-novo alternative to the existing methods.
文摘In order to promote the efficiency of teachers’teaching and students’learning,based on the naturalistic inquiry,the study mainly describes the typical features of teacher talk.High quality language input rely on the teaching materials and curricu⁃lum design,more importantly,it relies on the teacher talk to express and explain language knowledge.The teacher talk has an influ⁃ence on learners’learning attitude,classroom performance and the learning process.If used appropriately,the teacher talk can pro⁃mote the communication as well as inspire students to participate the classroom interaction.
文摘The study was conducted to evaluate the effect of baking conditions of partially-dried potato slices (PDPS) prior baking on the quality attributes of the resultant baked potato chips. Baking experiment was conducted at power levels of 80 and 100 Watts for different baking times according to microwave power used. Texture, color measurements and sensory evaluation were carried out on resultant baked potato chips. The results showed that partially drying step (even to 40% moisture content) prior microwave baking resulted in marked crispiness as well as brilliant yellow in resultant potato chips. The optimum conditions for the best quality of partially-dried potato chips were microwave cooking at power level of 100 Watts for 100 seconds.
文摘Background: A Randomized Controlled Trial (RCT) has been elaborated where goal directed fluid and hemodynamic therapy (GDFHT) will be realized with trans-thoracic echocardiographic aortic blood flow peak velocity variation (ΔVpeak) and distance minute (DM) to guide fluid therapy and hemodynamics in high risk pediatric surgical patients. This RCT will clarify the impact of GDFHT with ΔVpeak and DM on postoperative outcome in terms of morbidity, length of stay in the intensive care unit (LOSICU), length of mechanical ventilation (LMV) and length of hospital stay (LOS) in children. To determine values of ΔVpeak, DM and VTI predictive of these postoperative outcomes, an observational pilot study will be realized. This pilot study is described here. The primary objective of this study is to determine values of ΔVpeak, DM and ITV predictive of postoperative outcome in children in terms of morbidity. The secondary objectives are to determine values of ΔVpeak, DM and ITV predictive of LOSICU, LMV, LOS, intraoperative, postoperative fluid administration and vasoactive-inotropic therapy. Methods: 500 - 1000 children aged less than 18 years will be included prospectively. Statistic analysis will be realized with XLSTAT 2019.4.2 software or plus. Results and Conclusions: This trial protocol will determine values of ΔVpeak, DM and ITV with echocardiography predictive of postoperative outcome in children.
基金supported by the National Natural Science Foundation of China(No.71671100)the Joint Research Scheme of the National Natural Science Foundation of China/Research Grants Council of Hong Kong(Nos.71561167001 and N HKU707)+1 种基金the Director Foundation Project of National Engineering Laboratory for Public Safety Risk Perception and Control by Big Data(PSRPC)the Research Funds of Tsinghua University(No.20151080412).
文摘Research into the impact of road accidents on drivers is essential to effective post-crash interventions.However,due to limited data and resources,the current research focus is mainly on those who have suffered severe injuries.In this paper,we propose a novel approach to examining the impact that being involved in a crash has on drivers by using traffic surveillance data.In traffic video surveillance systems,the locations of vehicles at different moments in time are captured and their headway,which is an important indicator of driving behavior,can be calculated from this information.It was found that there was a sudden increase in headway when drivers return to the road after being involved in a crash,but that the headway returned to its pre-crash level over time.We further analyzed the duration of the decay using a Cox proportional hazards regression model,which revealed many significant factors(related to the driver,vehicle,and nature of the accident)behind the survival time of the increased headway.Our approach is able to reveal the crash impact on drivers in a convenient and economical way.It can enhance the understanding of the impact of a crash on drivers,and help to devise more effective re-education programs and other interventions to encourage drivers who are involved in crashes to drive more safely in the future.
文摘In the modern era of manufacturing, it is important to optimize every design parameter in product development stage to reduce cost, material usage and to achieve the desired efficacy level. There are various models which serve those purposes, for instance, Design of Experiment (DoE) is used to check the parameters after adopting optimization tactics which results in reduced cost or saving operating time. In this regard, this research aims to construct a DoE model on a portable workstation to optimize its design parameters. The methodology of DOE would be a 2 level 3 factors full factorial DOE which is conducted to determine the optimal value for three design parameters (factors) which are material density, the length of the table and the length of the table stand in terms of the response which is the required time of fold ability function of the portable workstation. Based upon the evaluated interactions between the parameters, the optimized parameters are chosen for responses. Here, the resultant design parameters are at their lowest level, so the goal of time efficiency in fold ability function is achieved. This similar sort of DoE can be implemented in the furniture and other manufacturing industries who wish to optimize their material usage as well as increase efficiency and reduce cycle time.