The Loess Plateau is an earthquake prone region of China, where the effects of loess deposit on ground motion were discovered during the 2008 Wenchuan earthquake(Ms8.0) and the 2013 Minxian-Zhangxian earthquake(Ms6.6)...The Loess Plateau is an earthquake prone region of China, where the effects of loess deposit on ground motion were discovered during the 2008 Wenchuan earthquake(Ms8.0) and the 2013 Minxian-Zhangxian earthquake(Ms6.6). The field investigations, observations, and analyses indicated that large number of casualties and tremendous economic losses were caused not only by collapse and damage of houses with poor seismic performance, landslides, but also amplification effects of site conditions, topography and thickness of loess deposit, on ground motion. In this paper, we chose Dazhai Village and Majiagou Village as the typical loess site affected by the two earthquakes for intensity evaluation, borehole exploration, temporary strong motion array, micro tremor survey, and numerical analysis. The aim is to explore the relations between amplification factors and site conditions in terms of topography and thickness of loess deposit. We also developed site amplification factors of ground motion for engineering design consideration at loess sites. The results showed that the amplification effects are more predominant with increase in thickness of loess deposit and slope height. The amplification mayincrease seismic intensity by 1 degree, PGA and predominant period by 2 times, respectively.展开更多
Plant extracts are widely studied for their anti-cancer and cancer preventive effects. In this study, we compared the leukemia growth inhibition effects of seven different plant extracts, theaflavin, epigallocatechin ...Plant extracts are widely studied for their anti-cancer and cancer preventive effects. In this study, we compared the leukemia growth inhibition effects of seven different plant extracts, theaflavin, epigallocatechin gallate (EGCG), epicathechin (EC), apigenin, quercetin, chrysin and tannic acid, in vitro using the K562 erythroleukemia cell line and application of the design of experiments (DoE) methodology. Our systematic approach enabled us to isolate the main factor contribution, two-factor interactions and produced interaction relationships and/or models to describe growth inhibitory effects of different plant extracts when they are used in combination. The results identified tannic acid as the most significant inhibitor in this group and had synergistic effects with EGCG at specific concentrations. The fitted model of their combined effects showed that the most potent combination is at low concentrations of tannic acid (10 - 20 μM) and high concentrations of EGCG (80 - 100 μM). We further showed that tannic acid induced both growth inhibition and apoptosis in K562 cells in ranges between 10 - 100 μM. The polyphenol caused cell cycle arrest at G2- phase under the higher concentrations. In summary, use of DoE techniques effectively identified the most prominent inducer in this group of plant bioactive compounds and produced combinatorial bioactivity of various polyphenols and flavonoids over the entire range of concentrations under study. This study exemplifies the usefulness of DoE and serves as a guide in its utility for in vitro assessment of bioactivity in plant constituents.展开更多
In this paper, the effect of the grinding undercut of the raceways on the longitudinal pressure distribution of the profiled rollers, which are the most popular axial profile employed by the bearing manufacturers, was...In this paper, the effect of the grinding undercut of the raceways on the longitudinal pressure distribution of the profiled rollers, which are the most popular axial profile employed by the bearing manufacturers, was discussed. Based on the profiled roller geometrical equations and numerical calculation of three dimensional elastic contact problems of finite length, a new numerical method for calculating the crown drop evaluation considering the effect of grinding undercut was used. The analyses of two structure case, that roller length is greater or less than raceway width, were carried out and compared with each other. The Results show that the width of grinding undercut must be considered in determining the crown drop of rollers.展开更多
Based on the thermal network of the two-dimensional heterojunction bipolar transistors(HBTs) array, the thermal resistance matrix is presented, including the self-heating thermal resistance and thermal coupling resist...Based on the thermal network of the two-dimensional heterojunction bipolar transistors(HBTs) array, the thermal resistance matrix is presented, including the self-heating thermal resistance and thermal coupling resistance to describe the self-heating and thermal coupling effects, respectively.For HBT cells along the emitter length direction, the thermal coupling resistance is far smaller than the self-heating thermal resistance, and the peak junction temperature is mainly determined by the self-heating thermal resistance.However, the thermal coupling resistance is in the same order with the self-heating thermal resistance for HBT cells along the emitter width direction.Furthermore, the dependence of the thermal resistance matrix on cell spacing along the emitter length direction and cell spacing along the emitter width direction is also investigated, respectively.It is shown that the moderate increase of cell spacings along the emitter length direction and the emitter width direction could effectively lower the self-heating thermal resistance and thermal coupling resistance,and hence the peak junction temperature is decreased, which sheds light on adopting a two-dimensional non-uniform cell spacing layout to improve the uneven temperature distribution.By taking a 2 × 6 HBTs array for example, a twodimensional non-uniform cell spacing layout is designed, which can effectively lower the peak junction temperature and reduce the non-uniformity of the dissipated power.For the HBTs array with optimized layout, the high power-handling capability and thermal dissipation capability are kept when the bias voltage increases.展开更多
Background and Objective: A multitude of large cohort studies have collected data on incidence and covariates/risk factors of various chronic diseases. However, approaches for utilization of these large data and trans...Background and Objective: A multitude of large cohort studies have collected data on incidence and covariates/risk factors of various chronic diseases. However, approaches for utilization of these large data and translation of the valuable results to inform and guide clinical disease prevention practice are not well developed. In this paper, we proposed, based on large cohort study data, a novel conceptual cost-effective disease prevention design strategy for a target group when it is not affordable to include everyone in the target group for intervention. Methods and Results: Data from American Indian participants (n = 3516;2056 women) aged 45 - 74 years in the Strong Heart Study, the diabetes risk prediction model from the study, a utility function, and regression models were used. A conceptual cost-effective disease prevention design strategy based on large cohort data was initiated. The application of the proposed strategy for diabetes prevention was illustrated. Discussion: The strategy may provide reasonable solutions to address cost-effective prevention design issues. These issues include complex associations of a disease with its significant risk factors, cost-effectively selecting individuals at high risk of developing disease to undergo intervention, individual differences in health conditions, choosing intervention risk factors and setting their appropriate, attainable, gradual and adaptive goal levels for different subgroups, and assessing effectiveness of the prevention program. Conclusions: The strategy and methods shown in the illustrative example can also be analogously adopted and applied to other diseases preventions. The proposed strategy provides a way to translate and apply epidemiological study results to clinical disease prevention practice.展开更多
Concept of city square was introduced and believed as an important component of urban landscape and also a major space for urban residents' activities. Beauty of city square lies in the interaction between environ...Concept of city square was introduced and believed as an important component of urban landscape and also a major space for urban residents' activities. Beauty of city square lies in the interaction between environment and social behaviors. By introducing the two-way interaction between city square and users, behavior psychology was proposed as the foundation of environment design of plaza. As more and more attention is given to humancentered design of outdoor spaces, environment psychology has gradually been more applied in the design of various urban landscape spaces. In view of problems in the present square design, relevant theories of environment psychology were introduced to analyze psychological needs and behavior characteristics of people in outdoor spaces, and techniques for human- centered designs of city square explored to build public spaces for city dwellers.展开更多
In modem packaging design, color, as an element of the intense visual impact, plays a very important role, and also can effectively enhance the effect of commercial packaging. However, uniqueness is necessarily availa...In modem packaging design, color, as an element of the intense visual impact, plays a very important role, and also can effectively enhance the effect of commercial packaging. However, uniqueness is necessarily available in the design of packaging according to the increase of consumer demand and the increasingly fierce market competition, while one of the effective ways to improve the effect of packaging design is to make full use of nationalities decorative colors. In this paper, the use of nationalities decorative colors in the modem packaging design is studied.展开更多
In order to obtain optimized flight vehicle concepts which meet system of systems （SOS） operation requirements, designers have to pay high attention to the impact of SoS at conceptual design stage since operation en...In order to obtain optimized flight vehicle concepts which meet system of systems （SOS） operation requirements, designers have to pay high attention to the impact of SoS at conceptual design stage since operation environment goes increasingly complex. Based on this tendency, per- spectives and progre,;ses of SoS oriented flight vehicle conceptual design, which is abbreviate as SoSed design, are reviewed in this paper. Such basic concepts of SoS as definition, characteristics, differences between systems engineering and SoS engineering, as well as SoSed design process are introduced, then SoS engineering process model for research and development of flight vehicles and SoSed design wheel model for conceptual design are proposed. Related literature is classified and analyzed in accordance with four major elements including requirements, design concept, design analysis, and trade studies and optimization： typical SoS architectures, description and quan- tization of indexes are introduced; Application of inverse design in designing concept is analyzed; Modeling and simulation （M＆S）-based methods and their applications in SoSed effectiveness evaluation are highlighted; According to SoSed trade studies and optimization related research, the importance of such points as decision-making and using multidisciplinary design optimization for reference are emphasized. Finally, the value of SoSed design is concluded, and five directions which are worthy of .attention in this field are presented.展开更多
Robust parameter design （RPD） is an important issue in experimental designs. If all experimental runs cannot be performed under homogeneous conditions, blocking the units is effective. In this paper, we obtain the c...Robust parameter design （RPD） is an important issue in experimental designs. If all experimental runs cannot be performed under homogeneous conditions, blocking the units is effective. In this paper, we obtain the correspondence relation between fractional factorial RPDs and the blocking schemes for full factorial RPDs. In addition, we provide a construction of optimal blocking schemes that make all main effects and control-by-noise two-factor interactions estimable.展开更多
The evaluation of training effectiveness （TE） of military training aircraft, though obviously very important, appears to have attracted much less attention than what it deserves in the open literature. This article ...The evaluation of training effectiveness （TE） of military training aircraft, though obviously very important, appears to have attracted much less attention than what it deserves in the open literature. This article aims to start from previous studies and explore further. First, TE of military training aircraft is discussed and our ideas for evaluating TE which are expressed mathematically are proposed. Then, using the presented mathematical models, software is developed that takes into consideration the influence of parameters of flight performance and quality on TE. The software＇s environment is Borland C＋＋ and it sets up the parameters of trainer, training standard databases and training documents; it can analyze and then give the operational cost and cost-effectiveness ratio of military trainer. Finally, the software is utilized to compare the TEs of HAWK and MB339 with that of Chinese Air Force TF-6. The results of comparison show that the TE of TF-6 is the lowest.展开更多
Compared with a delta wing aircraft, the double delta wing configuration has better aerodynamic performance at high angles of attack. An operational analysis was introduced as a method for evaluating training effecti...Compared with a delta wing aircraft, the double delta wing configuration has better aerodynamic performance at high angles of attack. An operational analysis was introduced as a method for evaluating training effectiveness of trainer aircraft. Approaches to the engineering estimation of aerodynamic characteristics for aircraft with a double delta wing configuration were studied, and the procedures for determining aircraft performance indices formulated. Taking training effectiveness as the objective function and geometric parameters of the wing platform as design variables, through a numerical multivariate optimization arithmetic, the conceptual design optimization for a certain fighter trainer aircraft with double delta wing configuration was carried out under the constraints of tactical and technical requirements and interrelated geometry. Agreement of a calculation example with engineering practice indicates that the optimal design has higher training effectiveness than the baseline design, and in addition, improves the structural force bearing conditions.展开更多
The heavy fuel compression ignition engines are widely equipped as aircraft piston engines. The fuel injection system is one of the key technologies that determines the performance of engine. One of the main challenge...The heavy fuel compression ignition engines are widely equipped as aircraft piston engines. The fuel injection system is one of the key technologies that determines the performance of engine. One of the main challenges is to precisely control the injected fuel quantity and flow rate in the presence of pressure fluctuation. This challenge is even more serious for heavy fuel. An original design for electrically controlled high pressure fuel injection system called Multi-Pumppressure-reservoirs fuel injection System(MPS) was demonstrated to reduce the pressure fluctuation and help keep injection stable. MPS was compared with an ordinary high pressure Common Rail fuel injection System(CRS). This work established one-dimensional AMESim and mathematical models for both CRS and MPS to study the effect of different structures and geometric parameters on the pressure fluctuations. The calculations show that the average fuel pressure fluctuation of MPS can be reduced by 57% for the crankshaft speed of 1900 r/min, and the pressure fluctuation before injection reduced by 100%. It is concluded that the pressure performance of MPS is less sensitive to pressure reservoir volume than that of CRS, and there is an opportunity for further volume reduction.展开更多
The angular acceleration due to the spin effect increases the burning rate of solid propellant and changes the motor performance by increasing the operating pressure and decreasing the burning time. So it is important...The angular acceleration due to the spin effect increases the burning rate of solid propellant and changes the motor performance by increasing the operating pressure and decreasing the burning time. So it is important to know the grain regression taken place in the solid propellant rocket motor in the acceleration field. This study represents the grain regression analysis of two-dimensional axis-symmetric star grain configuration of the solid propellant rocket motor with spin induced acceleration effect and pressure effect on burn rate using geometrical and numerical analysis. While the rocket is spinning, the burn rates on each point of the propellant surface are different with its radial distance, acceleration vector angle and surface slope. With the different burn rates on the propellant surface, we analyze the propellant surface perimeter and port area, and these results are compared with those of constant burn rate and burn rate affected by the chamber pressure.展开更多
基金financially supported by National Natural Science Foundation of China (No.51478444 & No.41472297)
文摘The Loess Plateau is an earthquake prone region of China, where the effects of loess deposit on ground motion were discovered during the 2008 Wenchuan earthquake(Ms8.0) and the 2013 Minxian-Zhangxian earthquake(Ms6.6). The field investigations, observations, and analyses indicated that large number of casualties and tremendous economic losses were caused not only by collapse and damage of houses with poor seismic performance, landslides, but also amplification effects of site conditions, topography and thickness of loess deposit, on ground motion. In this paper, we chose Dazhai Village and Majiagou Village as the typical loess site affected by the two earthquakes for intensity evaluation, borehole exploration, temporary strong motion array, micro tremor survey, and numerical analysis. The aim is to explore the relations between amplification factors and site conditions in terms of topography and thickness of loess deposit. We also developed site amplification factors of ground motion for engineering design consideration at loess sites. The results showed that the amplification effects are more predominant with increase in thickness of loess deposit and slope height. The amplification mayincrease seismic intensity by 1 degree, PGA and predominant period by 2 times, respectively.
文摘Plant extracts are widely studied for their anti-cancer and cancer preventive effects. In this study, we compared the leukemia growth inhibition effects of seven different plant extracts, theaflavin, epigallocatechin gallate (EGCG), epicathechin (EC), apigenin, quercetin, chrysin and tannic acid, in vitro using the K562 erythroleukemia cell line and application of the design of experiments (DoE) methodology. Our systematic approach enabled us to isolate the main factor contribution, two-factor interactions and produced interaction relationships and/or models to describe growth inhibitory effects of different plant extracts when they are used in combination. The results identified tannic acid as the most significant inhibitor in this group and had synergistic effects with EGCG at specific concentrations. The fitted model of their combined effects showed that the most potent combination is at low concentrations of tannic acid (10 - 20 μM) and high concentrations of EGCG (80 - 100 μM). We further showed that tannic acid induced both growth inhibition and apoptosis in K562 cells in ranges between 10 - 100 μM. The polyphenol caused cell cycle arrest at G2- phase under the higher concentrations. In summary, use of DoE techniques effectively identified the most prominent inducer in this group of plant bioactive compounds and produced combinatorial bioactivity of various polyphenols and flavonoids over the entire range of concentrations under study. This study exemplifies the usefulness of DoE and serves as a guide in its utility for in vitro assessment of bioactivity in plant constituents.
文摘In this paper, the effect of the grinding undercut of the raceways on the longitudinal pressure distribution of the profiled rollers, which are the most popular axial profile employed by the bearing manufacturers, was discussed. Based on the profiled roller geometrical equations and numerical calculation of three dimensional elastic contact problems of finite length, a new numerical method for calculating the crown drop evaluation considering the effect of grinding undercut was used. The analyses of two structure case, that roller length is greater or less than raceway width, were carried out and compared with each other. The Results show that the width of grinding undercut must be considered in determining the crown drop of rollers.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61006059 and 61774012)Beijing Municipal Natural Science Foundation,China(Grant No.4143059)+3 种基金Beijing Municipal Education Committee,China(Grant No.KM201710005027)Postdoctoral Science Foundation of Beijing,China(Grant No.2015ZZ-11)China Postdoctoral Science Foundation(Grant No.2015M580951)Scientific Research Foundation Project of Beijing Future Chip Technology Innovation Center,China(Grant No.KYJJ2016008)
文摘Based on the thermal network of the two-dimensional heterojunction bipolar transistors(HBTs) array, the thermal resistance matrix is presented, including the self-heating thermal resistance and thermal coupling resistance to describe the self-heating and thermal coupling effects, respectively.For HBT cells along the emitter length direction, the thermal coupling resistance is far smaller than the self-heating thermal resistance, and the peak junction temperature is mainly determined by the self-heating thermal resistance.However, the thermal coupling resistance is in the same order with the self-heating thermal resistance for HBT cells along the emitter width direction.Furthermore, the dependence of the thermal resistance matrix on cell spacing along the emitter length direction and cell spacing along the emitter width direction is also investigated, respectively.It is shown that the moderate increase of cell spacings along the emitter length direction and the emitter width direction could effectively lower the self-heating thermal resistance and thermal coupling resistance,and hence the peak junction temperature is decreased, which sheds light on adopting a two-dimensional non-uniform cell spacing layout to improve the uneven temperature distribution.By taking a 2 × 6 HBTs array for example, a twodimensional non-uniform cell spacing layout is designed, which can effectively lower the peak junction temperature and reduce the non-uniformity of the dissipated power.For the HBTs array with optimized layout, the high power-handling capability and thermal dissipation capability are kept when the bias voltage increases.
文摘Background and Objective: A multitude of large cohort studies have collected data on incidence and covariates/risk factors of various chronic diseases. However, approaches for utilization of these large data and translation of the valuable results to inform and guide clinical disease prevention practice are not well developed. In this paper, we proposed, based on large cohort study data, a novel conceptual cost-effective disease prevention design strategy for a target group when it is not affordable to include everyone in the target group for intervention. Methods and Results: Data from American Indian participants (n = 3516;2056 women) aged 45 - 74 years in the Strong Heart Study, the diabetes risk prediction model from the study, a utility function, and regression models were used. A conceptual cost-effective disease prevention design strategy based on large cohort data was initiated. The application of the proposed strategy for diabetes prevention was illustrated. Discussion: The strategy may provide reasonable solutions to address cost-effective prevention design issues. These issues include complex associations of a disease with its significant risk factors, cost-effectively selecting individuals at high risk of developing disease to undergo intervention, individual differences in health conditions, choosing intervention risk factors and setting their appropriate, attainable, gradual and adaptive goal levels for different subgroups, and assessing effectiveness of the prevention program. Conclusions: The strategy and methods shown in the illustrative example can also be analogously adopted and applied to other diseases preventions. The proposed strategy provides a way to translate and apply epidemiological study results to clinical disease prevention practice.
文摘Concept of city square was introduced and believed as an important component of urban landscape and also a major space for urban residents' activities. Beauty of city square lies in the interaction between environment and social behaviors. By introducing the two-way interaction between city square and users, behavior psychology was proposed as the foundation of environment design of plaza. As more and more attention is given to humancentered design of outdoor spaces, environment psychology has gradually been more applied in the design of various urban landscape spaces. In view of problems in the present square design, relevant theories of environment psychology were introduced to analyze psychological needs and behavior characteristics of people in outdoor spaces, and techniques for human- centered designs of city square explored to build public spaces for city dwellers.
文摘In modem packaging design, color, as an element of the intense visual impact, plays a very important role, and also can effectively enhance the effect of commercial packaging. However, uniqueness is necessarily available in the design of packaging according to the increase of consumer demand and the increasingly fierce market competition, while one of the effective ways to improve the effect of packaging design is to make full use of nationalities decorative colors. In this paper, the use of nationalities decorative colors in the modem packaging design is studied.
基金supported by the Fundamental Research Funds for the Central Universities of China
文摘In order to obtain optimized flight vehicle concepts which meet system of systems （SOS） operation requirements, designers have to pay high attention to the impact of SoS at conceptual design stage since operation environment goes increasingly complex. Based on this tendency, per- spectives and progre,;ses of SoS oriented flight vehicle conceptual design, which is abbreviate as SoSed design, are reviewed in this paper. Such basic concepts of SoS as definition, characteristics, differences between systems engineering and SoS engineering, as well as SoSed design process are introduced, then SoS engineering process model for research and development of flight vehicles and SoSed design wheel model for conceptual design are proposed. Related literature is classified and analyzed in accordance with four major elements including requirements, design concept, design analysis, and trade studies and optimization： typical SoS architectures, description and quan- tization of indexes are introduced; Application of inverse design in designing concept is analyzed; Modeling and simulation （M＆S）-based methods and their applications in SoSed effectiveness evaluation are highlighted; According to SoSed trade studies and optimization related research, the importance of such points as decision-making and using multidisciplinary design optimization for reference are emphasized. Finally, the value of SoSed design is concluded, and five directions which are worthy of .attention in this field are presented.
基金supported by the National Natural Science Foundation of China(1127120511271355+2 种基金11101024 and 11171165)the "131" Talents Program of Tianjinthe Fundamental Research Funds for the Central Universities(65030011 and 65011361)
文摘Robust parameter design （RPD） is an important issue in experimental designs. If all experimental runs cannot be performed under homogeneous conditions, blocking the units is effective. In this paper, we obtain the correspondence relation between fractional factorial RPDs and the blocking schemes for full factorial RPDs. In addition, we provide a construction of optimal blocking schemes that make all main effects and control-by-noise two-factor interactions estimable.
文摘The evaluation of training effectiveness （TE） of military training aircraft, though obviously very important, appears to have attracted much less attention than what it deserves in the open literature. This article aims to start from previous studies and explore further. First, TE of military training aircraft is discussed and our ideas for evaluating TE which are expressed mathematically are proposed. Then, using the presented mathematical models, software is developed that takes into consideration the influence of parameters of flight performance and quality on TE. The software＇s environment is Borland C＋＋ and it sets up the parameters of trainer, training standard databases and training documents; it can analyze and then give the operational cost and cost-effectiveness ratio of military trainer. Finally, the software is utilized to compare the TEs of HAWK and MB339 with that of Chinese Air Force TF-6. The results of comparison show that the TE of TF-6 is the lowest.
文摘Compared with a delta wing aircraft, the double delta wing configuration has better aerodynamic performance at high angles of attack. An operational analysis was introduced as a method for evaluating training effectiveness of trainer aircraft. Approaches to the engineering estimation of aerodynamic characteristics for aircraft with a double delta wing configuration were studied, and the procedures for determining aircraft performance indices formulated. Taking training effectiveness as the objective function and geometric parameters of the wing platform as design variables, through a numerical multivariate optimization arithmetic, the conceptual design optimization for a certain fighter trainer aircraft with double delta wing configuration was carried out under the constraints of tactical and technical requirements and interrelated geometry. Agreement of a calculation example with engineering practice indicates that the optimal design has higher training effectiveness than the baseline design, and in addition, improves the structural force bearing conditions.
文摘The heavy fuel compression ignition engines are widely equipped as aircraft piston engines. The fuel injection system is one of the key technologies that determines the performance of engine. One of the main challenges is to precisely control the injected fuel quantity and flow rate in the presence of pressure fluctuation. This challenge is even more serious for heavy fuel. An original design for electrically controlled high pressure fuel injection system called Multi-Pumppressure-reservoirs fuel injection System(MPS) was demonstrated to reduce the pressure fluctuation and help keep injection stable. MPS was compared with an ordinary high pressure Common Rail fuel injection System(CRS). This work established one-dimensional AMESim and mathematical models for both CRS and MPS to study the effect of different structures and geometric parameters on the pressure fluctuations. The calculations show that the average fuel pressure fluctuation of MPS can be reduced by 57% for the crankshaft speed of 1900 r/min, and the pressure fluctuation before injection reduced by 100%. It is concluded that the pressure performance of MPS is less sensitive to pressure reservoir volume than that of CRS, and there is an opportunity for further volume reduction.
文摘The angular acceleration due to the spin effect increases the burning rate of solid propellant and changes the motor performance by increasing the operating pressure and decreasing the burning time. So it is important to know the grain regression taken place in the solid propellant rocket motor in the acceleration field. This study represents the grain regression analysis of two-dimensional axis-symmetric star grain configuration of the solid propellant rocket motor with spin induced acceleration effect and pressure effect on burn rate using geometrical and numerical analysis. While the rocket is spinning, the burn rates on each point of the propellant surface are different with its radial distance, acceleration vector angle and surface slope. With the different burn rates on the propellant surface, we analyze the propellant surface perimeter and port area, and these results are compared with those of constant burn rate and burn rate affected by the chamber pressure.
