The safety and the fatigue comfort were compared between a domestic and a Japanese postal bicycle. Firstly, the fatigue comfort of these two kinds of bicycles was evaluated by surface electromyographic signal (sEMG) e...The safety and the fatigue comfort were compared between a domestic and a Japanese postal bicycle. Firstly, the fatigue comfort of these two kinds of bicycles was evaluated by surface electromyographic signal (sEMG) experiment, in which human lower limb muscle groups were research objects, and the average EMG (AEMG) index and median frequency (MF) were chosen as the evaluation indexes. Secondly, the safety of these two kinds of bicycle frames was analyzed and compared by using the finite element analysis. The results show that the riding fatigue comfort of the Japanese postal bicycle is better, and the Japanese postal bicycle frame is more safe and reasonable although both the postal bicycles meet the requirement for strength. Finally, based on the above analysis, the frame structure and related parameters of the domestic postal bicycle were improved with reference to the Japanese postal bicycle and biomechanics theory.展开更多
The least means squares (LMS) adaptive filter algorithm was used in active suspension system. By adjusting the weight of adaptive filter, the minimum quadratic performance index was obtained. For two-degree-of-freed...The least means squares (LMS) adaptive filter algorithm was used in active suspension system. By adjusting the weight of adaptive filter, the minimum quadratic performance index was obtained. For two-degree-of-freedom vehicle suspension model, LMS adaptive controller was designed. The acceleration of the sprung mass,the dynamic tyre load between wheels and road,and the dynamic deflection between sprung mass and unsprung mass were determined as the evaluation targets of suspension performance. For LMS adaptive control suspension, compared with passive suspension, acceleration power spectral density of sprung mass acceleration under the road input model decreased 8-10 times in high frequency resonance band or low frequency resonance band. The simulation results show that LMS adaptive control is simple and remarkably effective. It further proves that the active control suspension system can improve both the riding comfort and handling safety in various operation conditions, and the method is fit for the active control of the suspension system.展开更多
Existing research on data collection using wireless mobile vehicle network emphasizes the reliable delivery of information.However,other performance requirements such as life cycle of nodes,stability and security are ...Existing research on data collection using wireless mobile vehicle network emphasizes the reliable delivery of information.However,other performance requirements such as life cycle of nodes,stability and security are not set as primary design objectives.This makes data collection ability of vehicular nodes in real application environment inferior.By considering the features of nodes in wireless IoV,such as large scales of deployment,volatility and low time delay,an efficient data collection algorithm is proposed for mobile vehicle network environment.An adaptive sensing model is designed to establish vehicular data collection protocol.The protocol adopts group management in model communication.The vehicular sensing node in group can adjust network sensing chain according to sensing distance threshold with surrounding nodes.It will dynamically choose a combination of network sensing chains on basis of remaining energy and location characteristics of surrounding nodes.In addition,secure data collection between sensing nodes is undertaken as well.The simulation and experiments show that the vehicular node can realize secure and real-time data collection.Moreover,the proposed algorithm is superior in vehicular network life cycle,power consumption and reliability of data collection by comparing to other algorithms.展开更多
AIM: To evaluate if the guidelines for the appro-priateness of performing colonoscopy by American Society for Gastrointestinal Endoscopy (AGSE) and Italian Society of Digestive Endoscopy (SIED) yield a good diagnostic...AIM: To evaluate if the guidelines for the appro-priateness of performing colonoscopy by American Society for Gastrointestinal Endoscopy (AGSE) and Italian Society of Digestive Endoscopy (SIED) yield a good diagnostic efficacy and do not present risks of missing important colonic pathologies in an Italian population sample.METHODS: A total of 1017 consecutive patients (560 men and 457 women; mean age 64.4 ± 16 years) referred to an open-access endoscopy unit for colonoscopy from July 2004 to May 2006 were evaluated according to ASGE and SIED guidelines for appropriateness of performing the procedure. Diagnostic yield was defined as the percentage of relevant colonic pathologies of the total number of colonoscopies performed.RESULTS: About 85.2% patients underwent colono-scopy that was considered appropriate based on at least one ASGE or SIED criterion, while it was considered inappropriate for 14.8% of patients. The diagnostic yield of colonoscopy was significantly higher for appropriate colonoscopies (26.94% vs 10.6%, P < 0.001) than for inappropriate colonoscopies (5.3%). There was no missed colorectal cancer following the ASGE/SIED criteria.CONCLUSION: ASGE/SIED guidelines have shown a good diagnostic yield and the rate of missing relevant colonic pathologies seems very low. Unfortunately, the percentage of inappropriate referrals for colonoscopy in an open-access endoscopy system is still high, despite the number of papers published on the issue and the definition of international guidelines. Further steps are required to update and standardize the guidelines to increase their diffusion and to promote educational programs for general practitioners.展开更多
In order to screen excellent tobacco varieties/lines that can be promoted in Ankang tobacco-growing area, this article analyzed the growth stages, botanical characteristics, agronomic characteristics, disease resistan...In order to screen excellent tobacco varieties/lines that can be promoted in Ankang tobacco-growing area, this article analyzed the growth stages, botanical characteristics, agronomic characteristics, disease resistance, flue-cured leaf appearance and economic characteristics of five tobacco varieties (lines): Yunyan 99, Yunyan 105, 6517, PVH19 and K326. The results showed that, compared with the control K326, Yunyan 105 had good appearance of flue-cured leaves, long growth duration and high disease resistance; its floral buds appeared early; it produced 22.8 leaves per plant, high yield of 2 134.5 kg/hm2 and high economic output of 39 274.8 Yuan/hm2. The percentage of first-class leaves of Yunyan 105 reached 39.07%, and the weight per leaf was 8.4 g. Yunyan 99 also had good appearance of flue-cured leaves, large stem diameter, large middle leaves high disease resistance; the sand leaves of Yunyan 99 matured early; its tobacco leaf yield was 2 058 kg/hm2, and its economic output reached 36 838.5 Yuan/hm2; the percentage of first-class leaves of Yunyan 99 was 40.4%. In summary, both Yunyan 105 and Yunyan 99 performed well in all tested traits, and thus can be selectively planted in Ankang tobaccogrowing area.展开更多
Objective: We described the applicability and evaluated the advantages of improved laparoscopic transanal pull-through (ILTPT) for low-rectal cancer resection. Materials: ILTPT was performed in 4 patients. Five or...Objective: We described the applicability and evaluated the advantages of improved laparoscopic transanal pull-through (ILTPT) for low-rectal cancer resection. Materials: ILTPT was performed in 4 patients. Five or 4 ports were used. After isolation and section of the inferior mesenteric vessels, the rectum and sigmoid colon was mobilized. Total mesorectal excision and dissection of the distal rectum from the puborectalis muscle was carried out under laparoscopic guidance. The sigmoid colon and rectum were exteriorized via the anus. The rectum was divided proximally. Next, a purse-string suture was placed in the proximal segment, and the distal end of the sigmoid colon was returned to the pelvic cavity. The distal rectum was divided with Curved cutter staplermade by Jonson-Jonson company. Dislodging specimen, the continuity of the intestinal tract was restored using PROXIMATE ILS Curved and Straight Intraluminal Staplers CDH29/33 (Ethicon) through the rectum. Results: None of the cases were converted to open surgery. Average operation time was 180 min (range, 160-210 min). No blood loss or any other complications were noted. Average postoperative stay was 9 days. Complications such as necrosis, anastomotic leakage and stricture, and genitoudnary disorders were not found in any of the patients at the 1 m follow-up. Conclusion: This report suggests that ILTPT is feasible and safe in Anus-Conserving Operation for low Rectal Cancer without auxiliary incision. If only we hold the applicability of ILTPT less trauma, more beautiful.展开更多
Attribute revocation is inevitable and al- so important for Attribute-Based Encryption (ABE) in practice. However, little attention has been paid to this issue, and it retrains one of the rmin obsta-cles for the app...Attribute revocation is inevitable and al- so important for Attribute-Based Encryption (ABE) in practice. However, little attention has been paid to this issue, and it retrains one of the rmin obsta-cles for the application of ABE. Most of existing ABE schemes support attribute revocation work under indirect revocation model such that all the users' private keys will be affected when the revo-cation events occur. Though some ABE schemes have realized revocation under direct revocation model such that the revocation list is embedded in the ciphertext and none of the users' private keys will be affected by revocation, they mostly focused on the user revocation that revokes the user's whole attributes, or they can only be proven to be selectively secure. In this paper, we first define a model of adaptively secure ABE supporting the at- tribute revocation under direct revocation model. Then we propose a Key-Policy ABE (KP-ABE) scheme and a Ciphertext-Policy ABE (CP-ABE) scheme on composite order bilinear groups. Finally, we prove our schemes to be adaptively secure by employing the methodology of dual system eno cryption.展开更多
In view of the fact that climate-related disasters are already taking a heavy toll, causing massive damage to crops and infrastructure and forcing some people to flee their homes, however, the potential impacts of cli...In view of the fact that climate-related disasters are already taking a heavy toll, causing massive damage to crops and infrastructure and forcing some people to flee their homes, however, the potential impacts of climate change are likely to trigger adaptive responses that influence environmental and socio-economic drivers of food system performance in positive as well as negative ways. This paper was conducted through the collection of some research materials with the projected balance of these various climate impacts on food system performance and food security outcomes at the local and global levels. More so that, food security is likely to be affected by climate change in several ways: food security depends not only on the direct impact of climate change on food production but also on its indirect impact on human nutrition and health, economic growth, trade flows and food aid policy. The paper further examined the effectiveness of managing new risks and uncertainty, improving the quality of information and its use, monitoring weather and improving scientific understanding of climate change, promoting insurance schemes, maintaining biodiversity and access to fund as some of the crucial measures for adaptation. The large amount of resources that would be necessary to avoid the worst case scenario suggests the necessity of continued support from the international community to improve food security at the local and global levels as a whole.展开更多
There are more than eight different design standards in use for the existing railway bridges in China, which have different applicabilities for bridges built in different periods. In this paper, the design load standa...There are more than eight different design standards in use for the existing railway bridges in China, which have different applicabilities for bridges built in different periods. In this paper, the design load standards in different periods are introduced and compared; The working status of the railway is investigated. According to the developing trend of separating passenger and freight transports, by comparing the computed results of the bridge effect and the fatigue cumulative damage, the applicabilities of bearing capacity and fatigue are analyzed for existing bridges. The results indicate that the bearing capacities of 99% existing bridges are suitable for the demand of 26.5 t (axle-weight) freight trains. However, for culverts, bridges with spans less than 20 m, longitudinal and transverse beams of through bridges, suspenders of truss bridges and other locally-stressed members should be evaluated and reinforced due to the increasing axle-weight.展开更多
In order to screen new flue-cured tobacco varieties (lines) with mountain characteristics of Ankang tobacco growing area, the adaptable selection experiments of 6 newly introduced flue-cured tobacco varieties (line...In order to screen new flue-cured tobacco varieties (lines) with mountain characteristics of Ankang tobacco growing area, the adaptable selection experiments of 6 newly introduced flue-cured tobacco varieties (lines) were carried out at the 2 set test sites in Ankang producing areas with K326, 'Yunyan 87' and 'Qinyan 96' as controls. The results showed that YN105 had more leaves per plant and coordi- nate chemical composition, and the yield per unit area was 2 221.05 kg/hm2 with the single output of 33 960.00 yuan/hm^2. Its rate of high and medium class leaves was 80.17%, presenting good performances in testing varieties (lines). The flowering of YN99 was late but showed coordinate chemical composition, and the yield per unit area was 2 128.50 kg/hm^2 with the single output of 33 454.05 yuan/hm^2. Its rate of high and medium class leaves was 83.17%, which also had good perfor- mances in testing varieties (lines). It was recommended that YN105 and YN99 be moderate planted in Ankang tobacco growing area, but further experiment is needed to confirm.展开更多
Shipboard operations as a hazardous process require the human element to be aware of any operation risks. Since the concept of human error exposed to ample arguments, the introduction of human element concerns to prac...Shipboard operations as a hazardous process require the human element to be aware of any operation risks. Since the concept of human error exposed to ample arguments, the introduction of human element concerns to practices rather than other means is essential because the provenance of accidents is human error. HRA (human reliability assessment) is a theoretical framework to assess the human actions for predicting the potential human error probability of a certain given task or operation scenario. Furthermore, surveillance of the human performance is through the task by steps and sub-steps. The CREAM (cognitive reliability and error analysis method) tool is the second generation of HRA which emphasizes the features of the context and utilized as retrospective and prospective tool. The paper illustrates the basic and extended version of CREAM and its suitability for critical shipboard operations safety assessment.展开更多
The dynamic behavior of rotors is highly influenced by bearing characteristics. In previous works, the authors have shown that it may be beneficial to adapt the bearing behavior to the shaft behavior. Several adaptive...The dynamic behavior of rotors is highly influenced by bearing characteristics. In previous works, the authors have shown that it may be beneficial to adapt the bearing behavior to the shaft behavior. Several adaptive and active components will be developed in this paper in order to control the shaft dynamical amplitude. Different models of hydrodynamic bearings behavior are described. The Reynolds equation resolution may be done by numerical or analytical solutions. A physical analysis of the equation of thin films will identify the most sensitive parameters. The shaft flexibility is taking into account by a modal approach. The fluid-structure coupling process is a simulation, step by step, of the rotor behavior. At each step, the nonlinear fluid force is numerically calculated to obtain the unbalanced shaft response. The results, presented in this paper, concern the dynamic response of unbalanced shaft mounted in adaptive or active bearings: bearings with variable clearance, variable viscosity or variable housing speed. It is shown that the fluid bearing parameters must be adapted to the rotor speed (in particular near or far a critical speed). Then, the paper presents a new kind of active bearing. It works with a mechanical control of the housing position. Several parameters are tested and compared. The robustness of the dynamic control parameters is presented. In conclusion, the bearing adaptation could be very useful to control the shaft dynamic. This limits the effect of the critical speed, in particular by diminishing the shaft amplitude and the dynamic forces transmitted to the housing.展开更多
To describe the design approaches of IND-CCA2 (adaptive chosen ciphertext attack) secure public key encryption schemes systematically, the gaps between different kinds of intractable problems and IND-CCA2 security a...To describe the design approaches of IND-CCA2 (adaptive chosen ciphertext attack) secure public key encryption schemes systematically, the gaps between different kinds of intractable problems and IND-CCA2 security are studied. This paper points out that the construction of IND-CCA2 secure schemes is essentially to bridge these gaps. These gaps are categorized, analyzed and measured. Finally the methods to bridge these gaps are described. This explains the existing design approaches and gives an intuition about the difficulty of designing IND-CCA2 secure public key encryption schemes based on different types of assumptions.展开更多
基金Supported by Special Fund Project for Technology Innovation of Tianjin (No.10FDZDGX00500)Tianjin Product Quality Inspection Technology Research Institute
文摘The safety and the fatigue comfort were compared between a domestic and a Japanese postal bicycle. Firstly, the fatigue comfort of these two kinds of bicycles was evaluated by surface electromyographic signal (sEMG) experiment, in which human lower limb muscle groups were research objects, and the average EMG (AEMG) index and median frequency (MF) were chosen as the evaluation indexes. Secondly, the safety of these two kinds of bicycle frames was analyzed and compared by using the finite element analysis. The results show that the riding fatigue comfort of the Japanese postal bicycle is better, and the Japanese postal bicycle frame is more safe and reasonable although both the postal bicycles meet the requirement for strength. Finally, based on the above analysis, the frame structure and related parameters of the domestic postal bicycle were improved with reference to the Japanese postal bicycle and biomechanics theory.
文摘The least means squares (LMS) adaptive filter algorithm was used in active suspension system. By adjusting the weight of adaptive filter, the minimum quadratic performance index was obtained. For two-degree-of-freedom vehicle suspension model, LMS adaptive controller was designed. The acceleration of the sprung mass,the dynamic tyre load between wheels and road,and the dynamic deflection between sprung mass and unsprung mass were determined as the evaluation targets of suspension performance. For LMS adaptive control suspension, compared with passive suspension, acceleration power spectral density of sprung mass acceleration under the road input model decreased 8-10 times in high frequency resonance band or low frequency resonance band. The simulation results show that LMS adaptive control is simple and remarkably effective. It further proves that the active control suspension system can improve both the riding comfort and handling safety in various operation conditions, and the method is fit for the active control of the suspension system.
基金supported by the National Nature Science Foundation of China(Grant61572188)A Project Supported by Scientif ic Research Fund of Hunan Provincial Education Department(14A047)+4 种基金the Natural Science Foundation of Fujian Province(Grant no.2014J05079)the Young and Middle-Aged Teachers Education Scientific Research Project of Fujian province(Grant nos.JA13248JA14254 and JA15368)the special scientific research funding for colleges and universities from Fujian Provincial Education Department(Grant no.JK2013043)the Research Project supported by Xiamen University of Technology(YKJ15019R)
文摘Existing research on data collection using wireless mobile vehicle network emphasizes the reliable delivery of information.However,other performance requirements such as life cycle of nodes,stability and security are not set as primary design objectives.This makes data collection ability of vehicular nodes in real application environment inferior.By considering the features of nodes in wireless IoV,such as large scales of deployment,volatility and low time delay,an efficient data collection algorithm is proposed for mobile vehicle network environment.An adaptive sensing model is designed to establish vehicular data collection protocol.The protocol adopts group management in model communication.The vehicular sensing node in group can adjust network sensing chain according to sensing distance threshold with surrounding nodes.It will dynamically choose a combination of network sensing chains on basis of remaining energy and location characteristics of surrounding nodes.In addition,secure data collection between sensing nodes is undertaken as well.The simulation and experiments show that the vehicular node can realize secure and real-time data collection.Moreover,the proposed algorithm is superior in vehicular network life cycle,power consumption and reliability of data collection by comparing to other algorithms.
文摘AIM: To evaluate if the guidelines for the appro-priateness of performing colonoscopy by American Society for Gastrointestinal Endoscopy (AGSE) and Italian Society of Digestive Endoscopy (SIED) yield a good diagnostic efficacy and do not present risks of missing important colonic pathologies in an Italian population sample.METHODS: A total of 1017 consecutive patients (560 men and 457 women; mean age 64.4 ± 16 years) referred to an open-access endoscopy unit for colonoscopy from July 2004 to May 2006 were evaluated according to ASGE and SIED guidelines for appropriateness of performing the procedure. Diagnostic yield was defined as the percentage of relevant colonic pathologies of the total number of colonoscopies performed.RESULTS: About 85.2% patients underwent colono-scopy that was considered appropriate based on at least one ASGE or SIED criterion, while it was considered inappropriate for 14.8% of patients. The diagnostic yield of colonoscopy was significantly higher for appropriate colonoscopies (26.94% vs 10.6%, P < 0.001) than for inappropriate colonoscopies (5.3%). There was no missed colorectal cancer following the ASGE/SIED criteria.CONCLUSION: ASGE/SIED guidelines have shown a good diagnostic yield and the rate of missing relevant colonic pathologies seems very low. Unfortunately, the percentage of inappropriate referrals for colonoscopy in an open-access endoscopy system is still high, despite the number of papers published on the issue and the definition of international guidelines. Further steps are required to update and standardize the guidelines to increase their diffusion and to promote educational programs for general practitioners.
文摘In order to screen excellent tobacco varieties/lines that can be promoted in Ankang tobacco-growing area, this article analyzed the growth stages, botanical characteristics, agronomic characteristics, disease resistance, flue-cured leaf appearance and economic characteristics of five tobacco varieties (lines): Yunyan 99, Yunyan 105, 6517, PVH19 and K326. The results showed that, compared with the control K326, Yunyan 105 had good appearance of flue-cured leaves, long growth duration and high disease resistance; its floral buds appeared early; it produced 22.8 leaves per plant, high yield of 2 134.5 kg/hm2 and high economic output of 39 274.8 Yuan/hm2. The percentage of first-class leaves of Yunyan 105 reached 39.07%, and the weight per leaf was 8.4 g. Yunyan 99 also had good appearance of flue-cured leaves, large stem diameter, large middle leaves high disease resistance; the sand leaves of Yunyan 99 matured early; its tobacco leaf yield was 2 058 kg/hm2, and its economic output reached 36 838.5 Yuan/hm2; the percentage of first-class leaves of Yunyan 99 was 40.4%. In summary, both Yunyan 105 and Yunyan 99 performed well in all tested traits, and thus can be selectively planted in Ankang tobaccogrowing area.
基金Supported by a grant from the foundation of Department of Health of Jiangxi Province (No.20086002)
文摘Objective: We described the applicability and evaluated the advantages of improved laparoscopic transanal pull-through (ILTPT) for low-rectal cancer resection. Materials: ILTPT was performed in 4 patients. Five or 4 ports were used. After isolation and section of the inferior mesenteric vessels, the rectum and sigmoid colon was mobilized. Total mesorectal excision and dissection of the distal rectum from the puborectalis muscle was carried out under laparoscopic guidance. The sigmoid colon and rectum were exteriorized via the anus. The rectum was divided proximally. Next, a purse-string suture was placed in the proximal segment, and the distal end of the sigmoid colon was returned to the pelvic cavity. The distal rectum was divided with Curved cutter staplermade by Jonson-Jonson company. Dislodging specimen, the continuity of the intestinal tract was restored using PROXIMATE ILS Curved and Straight Intraluminal Staplers CDH29/33 (Ethicon) through the rectum. Results: None of the cases were converted to open surgery. Average operation time was 180 min (range, 160-210 min). No blood loss or any other complications were noted. Average postoperative stay was 9 days. Complications such as necrosis, anastomotic leakage and stricture, and genitoudnary disorders were not found in any of the patients at the 1 m follow-up. Conclusion: This report suggests that ILTPT is feasible and safe in Anus-Conserving Operation for low Rectal Cancer without auxiliary incision. If only we hold the applicability of ILTPT less trauma, more beautiful.
文摘Attribute revocation is inevitable and al- so important for Attribute-Based Encryption (ABE) in practice. However, little attention has been paid to this issue, and it retrains one of the rmin obsta-cles for the application of ABE. Most of existing ABE schemes support attribute revocation work under indirect revocation model such that all the users' private keys will be affected when the revo-cation events occur. Though some ABE schemes have realized revocation under direct revocation model such that the revocation list is embedded in the ciphertext and none of the users' private keys will be affected by revocation, they mostly focused on the user revocation that revokes the user's whole attributes, or they can only be proven to be selectively secure. In this paper, we first define a model of adaptively secure ABE supporting the at- tribute revocation under direct revocation model. Then we propose a Key-Policy ABE (KP-ABE) scheme and a Ciphertext-Policy ABE (CP-ABE) scheme on composite order bilinear groups. Finally, we prove our schemes to be adaptively secure by employing the methodology of dual system eno cryption.
文摘In view of the fact that climate-related disasters are already taking a heavy toll, causing massive damage to crops and infrastructure and forcing some people to flee their homes, however, the potential impacts of climate change are likely to trigger adaptive responses that influence environmental and socio-economic drivers of food system performance in positive as well as negative ways. This paper was conducted through the collection of some research materials with the projected balance of these various climate impacts on food system performance and food security outcomes at the local and global levels. More so that, food security is likely to be affected by climate change in several ways: food security depends not only on the direct impact of climate change on food production but also on its indirect impact on human nutrition and health, economic growth, trade flows and food aid policy. The paper further examined the effectiveness of managing new risks and uncertainty, improving the quality of information and its use, monitoring weather and improving scientific understanding of climate change, promoting insurance schemes, maintaining biodiversity and access to fund as some of the crucial measures for adaptation. The large amount of resources that would be necessary to avoid the worst case scenario suggests the necessity of continued support from the international community to improve food security at the local and global levels as a whole.
文摘There are more than eight different design standards in use for the existing railway bridges in China, which have different applicabilities for bridges built in different periods. In this paper, the design load standards in different periods are introduced and compared; The working status of the railway is investigated. According to the developing trend of separating passenger and freight transports, by comparing the computed results of the bridge effect and the fatigue cumulative damage, the applicabilities of bearing capacity and fatigue are analyzed for existing bridges. The results indicate that the bearing capacities of 99% existing bridges are suitable for the demand of 26.5 t (axle-weight) freight trains. However, for culverts, bridges with spans less than 20 m, longitudinal and transverse beams of through bridges, suspenders of truss bridges and other locally-stressed members should be evaluated and reinforced due to the increasing axle-weight.
基金Supported by the Key Scientific and Technological Project for the Development of Featured Tobacco Leaves of Shaanxi Tobacco Monopoly Bureau(ZDKJ20122008)~~
文摘In order to screen new flue-cured tobacco varieties (lines) with mountain characteristics of Ankang tobacco growing area, the adaptable selection experiments of 6 newly introduced flue-cured tobacco varieties (lines) were carried out at the 2 set test sites in Ankang producing areas with K326, 'Yunyan 87' and 'Qinyan 96' as controls. The results showed that YN105 had more leaves per plant and coordi- nate chemical composition, and the yield per unit area was 2 221.05 kg/hm2 with the single output of 33 960.00 yuan/hm^2. Its rate of high and medium class leaves was 80.17%, presenting good performances in testing varieties (lines). The flowering of YN99 was late but showed coordinate chemical composition, and the yield per unit area was 2 128.50 kg/hm^2 with the single output of 33 454.05 yuan/hm^2. Its rate of high and medium class leaves was 83.17%, which also had good perfor- mances in testing varieties (lines). It was recommended that YN105 and YN99 be moderate planted in Ankang tobacco growing area, but further experiment is needed to confirm.
文摘Shipboard operations as a hazardous process require the human element to be aware of any operation risks. Since the concept of human error exposed to ample arguments, the introduction of human element concerns to practices rather than other means is essential because the provenance of accidents is human error. HRA (human reliability assessment) is a theoretical framework to assess the human actions for predicting the potential human error probability of a certain given task or operation scenario. Furthermore, surveillance of the human performance is through the task by steps and sub-steps. The CREAM (cognitive reliability and error analysis method) tool is the second generation of HRA which emphasizes the features of the context and utilized as retrospective and prospective tool. The paper illustrates the basic and extended version of CREAM and its suitability for critical shipboard operations safety assessment.
文摘The dynamic behavior of rotors is highly influenced by bearing characteristics. In previous works, the authors have shown that it may be beneficial to adapt the bearing behavior to the shaft behavior. Several adaptive and active components will be developed in this paper in order to control the shaft dynamical amplitude. Different models of hydrodynamic bearings behavior are described. The Reynolds equation resolution may be done by numerical or analytical solutions. A physical analysis of the equation of thin films will identify the most sensitive parameters. The shaft flexibility is taking into account by a modal approach. The fluid-structure coupling process is a simulation, step by step, of the rotor behavior. At each step, the nonlinear fluid force is numerically calculated to obtain the unbalanced shaft response. The results, presented in this paper, concern the dynamic response of unbalanced shaft mounted in adaptive or active bearings: bearings with variable clearance, variable viscosity or variable housing speed. It is shown that the fluid bearing parameters must be adapted to the rotor speed (in particular near or far a critical speed). Then, the paper presents a new kind of active bearing. It works with a mechanical control of the housing position. Several parameters are tested and compared. The robustness of the dynamic control parameters is presented. In conclusion, the bearing adaptation could be very useful to control the shaft dynamic. This limits the effect of the critical speed, in particular by diminishing the shaft amplitude and the dynamic forces transmitted to the housing.
基金the National Natural Science Foundation of China(Nos.60573032,60773092,90604036)
文摘To describe the design approaches of IND-CCA2 (adaptive chosen ciphertext attack) secure public key encryption schemes systematically, the gaps between different kinds of intractable problems and IND-CCA2 security are studied. This paper points out that the construction of IND-CCA2 secure schemes is essentially to bridge these gaps. These gaps are categorized, analyzed and measured. Finally the methods to bridge these gaps are described. This explains the existing design approaches and gives an intuition about the difficulty of designing IND-CCA2 secure public key encryption schemes based on different types of assumptions.