Young Tom is four years old.He is bright(聪明的)and lovely(可爱的).His father and mother lovehim very much.His father works ina factory.He always has a lot ofwork to do.So his mother oftenfeeds(喂)him food and carries...Young Tom is four years old.He is bright(聪明的)and lovely(可爱的).His father and mother lovehim very much.His father works ina factory.He always has a lot ofwork to do.So his mother oftenfeeds(喂)him food and carrieshim in her arms.Tom is too pam-pered(娇惯的).展开更多
A general mathematical model of carrier-based aircraft ski jump take-off is derived based on tensor. The carrier, the aircraft body and the movable parts of the landing gears are treated as independent entities. These...A general mathematical model of carrier-based aircraft ski jump take-off is derived based on tensor. The carrier, the aircraft body and the movable parts of the landing gears are treated as independent entities. These entities are assembled into a multi-rigid-body system with flexible links. Dynamical equations of each entity are derived on the basis of the Newton law and the Euler transformation. Using the invariance property of the tensor, the dynamical and kinematical equations are converted to tensor forms which are invariant under time-dependent coordinate transformations. Then the tensor-formed equations are expressed by the matrix operation. Differential equation group of the matrix form is formulated for the programming. The closure of the model is discussed, and the simulation results are given.展开更多
This paper describes a dual-stroke acting hydraulic power take-off (PTO) system employed in the wave energy converter (WEC) with an inverse pendulum. The hydraulic PTO converts slow irregular reciprocating wave mo...This paper describes a dual-stroke acting hydraulic power take-off (PTO) system employed in the wave energy converter (WEC) with an inverse pendulum. The hydraulic PTO converts slow irregular reciprocating wave motions to relatively smooth, fast rotation of an electrical generator. The design of the hydraulic PTO system and its control are critical to maximize the generated power. A time domain simulation study and the laboratory experiment of the full-scale beach test are presented. The results of the simulation and laboratory experiments including their comparison at full-scale are also presented, which have validated the rationality of the design and the reliability of some key components of the prototype of the WEC with an inverse pendulum with the dual-stroke acting hydraulic PTO system.展开更多
Among the wave energy converters (WECs), oscillating buoy is a promising type for wave energy development in offshore area. Conventional single-freedom oscillating buoy WECs with linear power take-off (PTO) system are...Among the wave energy converters (WECs), oscillating buoy is a promising type for wave energy development in offshore area. Conventional single-freedom oscillating buoy WECs with linear power take-off (PTO) system are less efficient under off-resonance conditions and have a narrow power capture bandwidth. Thus, a multi-freedom WEC with a nonlinear PTO system is proposed. This study examines a multi-freedom WEC with 3 degrees of freedom: surge, heave and pitch. Three different PTO systems (velocity-square, snap through, and constant PTO systems) and a traditional linear PTO system are applied to the WEC. A time-domain model is established using linear potential theory and Cummins equation. The kinematic equation is numerically calculated with the fourth-order Runge–Kutta method. The optimal average output power of the PTO systems in all degrees of freedom are obtained and compared. Other parameters of snap through PTO are also discussed in detail. Results show that according to the power capture performance, the order of the PTO systems from the best to worst is snap through PTO, constant PTO, linear PTO and velocity-square PTO. The resonant frequency of the WEC can be adjusted to the incident wave frequency by choosing specific parameters of the snap through PTO. Adding more DOFs can make the WEC get a better power performance in more wave frequencies. Both the above two methods can raise the WEC’s power capture performance significantly.展开更多
A novel method for estimating the space range of battery-powered vertical take-off and landing(VTOL) aircraft is presented. The method is based on flight parameter optimization and numerical iteration. Subsystem model...A novel method for estimating the space range of battery-powered vertical take-off and landing(VTOL) aircraft is presented. The method is based on flight parameter optimization and numerical iteration. Subsystem models including required thrust, required power and battery discharge models are presented. The problem to be optimized is formulated, and then case study simulation is conducted using the established method for quantitative analysis. Simulation results show that the space range of battery-powered VTOL aircraft in a vertical plane is an oblate curve, which appears horizontally long but vertically short, and the peak point is not located on the vertical climb path. The method and results are confirmed by parameter analysis and validations.展开更多
The " Sharp Eagle” device is a wave energy converter of a hinged double floating body. The wave-absorbing floating body hinges on the semi-submerged floating body structure. Under the action of wave, the wave-ab...The " Sharp Eagle” device is a wave energy converter of a hinged double floating body. The wave-absorbing floating body hinges on the semi-submerged floating body structure. Under the action of wave, the wave-absorbing floating body rotates around the hinge point, and the wave energy can be converted into kinetic energy. In this paper, the power take-off system of " Sharp Eagle Ⅱ” wave energy converter (the second generation of " Sharp Eagle”) was studied, which adopts the hydraulic type power take-off system. The 0-1 power generation mode was applied in this system to make the " Sharp Eagle Ⅱ” operate under various wave conditions. The principle of power generation was introduced in detail, and the power take-off system was simulated. Three groups of different movement period inputs were used to simulate three kinds of wave conditions, and the simulation results were obtained under three different working conditions. In addition, the prototype of " Sharp Eagle Ⅱ” wave energy converter was tested on land and in real sea conditions. The experimental data have been collected, and the experimental data and simulation results were compared and validated. This work has laid a foundation for the design and application of the following " Sharp Eagle” series of devices.展开更多
Nowadays, the success of the new technology development and deployment process depends not only on technical, technological solutions, but also on solving the non-technological problems and crossing the societal and p...Nowadays, the success of the new technology development and deployment process depends not only on technical, technological solutions, but also on solving the non-technological problems and crossing the societal and psychological barriers. A large international European projects, GABRIEL1 had developed a maglev assisted aircraft take-off and landing, that was applied to conceptual design of aircraft and required on-board and ground systems, had analysed all impacts (effects of concept deployment on effectiveness, safety, security, noise, emissions) and had demonstrated the safe applicability by concept validation. The applied methodology, used methods and the results of the Gabriel projects had been described and discussed by 55 project deliverables. This paper has a special goal: investigating the problems and barriers of possible implementing of the radically new technology, aircraft MagLev assisted take-off and landing. The study was started by identification and classification of the problems and barriers. After it, the problems were systematically analysed by use of special methodology containing the understanding (description) of the problems, investigation of the possible solutions and discussing their applicability (mainly by use of the Gabriel project results). The paper has three major sections: 1) description of the Gabriel concept and project results, 2) introducing some related thoughts on general aspects of new technology developments, and 3) discussion on the problems and their solutions. The major classes of the problems are the 1) technical, technological problems as developing a radically new solution, landing the undercarriage-less aircraft on the magnetic tracks, 2) stakeholders’ problems as decision makers kicking against supporting the developments of so radically new technologies and 3) society barriers like society worrying on and fear of future passengers on flying by aircraft have not conventional undercarriage systems. The paper will show that these problems have safe and cost-effective solutions.展开更多
Passive dynamic walking has been developed as a possible explanation for the efficiency of the human gait. This paper presents a passive dynamic walking model with segmented feet, which makes the bipedal walking gait ...Passive dynamic walking has been developed as a possible explanation for the efficiency of the human gait. This paper presents a passive dynamic walking model with segmented feet, which makes the bipedal walking gait more close to natural human-like gait. The proposed model extends the simplest walking model with the addition of fiat feet and torsional spring based compliance on ankle joints and toe joints, to achieve stable walking on a slope driven by gravity. The push-off phase includes foot rotations around the toe joint and around the toe tip, which shows a great resemblance to human normal walking. This paper investigates the effects of the segmented foot structure on bipedal walking in simulations. The model achieves satisfactory walking results on even or uneven slopes.展开更多
The semi-round rigid feet would cause position-posture deviation problem because the actual foothold position is hardly known due to the rolling effect of the semi-round rigid feet during the robot walking. The positi...The semi-round rigid feet would cause position-posture deviation problem because the actual foothold position is hardly known due to the rolling effect of the semi-round rigid feet during the robot walking. The position-posture deviation problem may harm to the stability and the harmony of the robot, or even makes the robot tip over and fail to walk forward. Focused on the position-posture deviation problem of multi-legged walking robots with semi-round rigid feet, a new method of position-posture closed-loop control is proposed to solve the position-posture deviation problem caused by semi-round rigid feet, based on the inverse velocity kinematics of the multi-legged walking robots. The position-posture closed-loop control is divided into two parts: the position closed-loop control and the posture closed-loop control. Thus, the position-posture control for the robot which is a tight coupling and nonlinear system is decoupled. Co-simulations of position-posture open-loop control and position-posture closed-loop control by MATLAB and ADAMS are implemented, respectively. The co-simulation results verify that the position-posture closed-loop control performs well in solving the position-posture deviation problem caused by semi-round rigid feet.展开更多
While injuries of the upper extremity are widely discussed in rock climbers, reports about the lower extremity are rare. Nevertheless almost 50 percent of acute injuries involve the leg and feet. Acute injuries are ei...While injuries of the upper extremity are widely discussed in rock climbers, reports about the lower extremity are rare. Nevertheless almost 50 percent of acute injuries involve the leg and feet. Acute injuries are either caused by ground falls or rock hit trauma during a fall. Most frequently strains, contusions and fractures of the calcaneus and talus. More rare injuries, as e.g., osteochondral lesions of the talus demand a highly specialized care and case presentations with combined iliac crest graft and matrix associated autologous chondrocyte transplantation are given in this review. The chronic use of tight climbing shoes leads to overstrain injuries also. As the tight fit of the shoes changes the biomechanics of the foot an increased stress load is applied to the fore-foot. Thus chronic conditions as subungual hematoma, callosity and pain resolve. Also a high incidence of hallux valgus and hallux rigidus is described.展开更多
Background: Feet odor is a common sociomedical problem that affects the feet of human beings of different etiological factors. Multiple modalities of therapy have been used in the treatment of feet odor. Objective: To...Background: Feet odor is a common sociomedical problem that affects the feet of human beings of different etiological factors. Multiple modalities of therapy have been used in the treatment of feet odor. Objective: To evaluate the efficacy and safety of topical 15% zinc sulfate solution in the treatment of feet odor. Patients and Methods: This single blind, placebo, controlled therapeutic study was conducted at the Department of Dermatology-Baghdad Teaching Hospital, from March 2010 to July 2011. A total of 108 (88 males and 20 females) patients with feet odor were enrolled and were divided into 2 groups: Group A: treated with 15% zinc sulfate solution. Group B: treated with distilled water as placebo control group. Full history and examination were carried out including all relevant points. Four scoring had been used to assess the severity of odor in patients with bared feet Score 0: no odor, Score 1: mild odor, Score 2: moderate odor and Score 3: severe odor. Zinc sulfate solution 15% was applied to sole and toe webs once daily for two weeks, three times per week for next two weeks and followed by single application weekly as maintenance after clearance of odor for two months. Patients were seen every two weeks to be examined and to score the odor again and to record side effects. Results: Group A: Fifty patients completed the study, their ages ranged from 8 - 68 (33 + 14.5) years, while the duration of the disease ranged from 1 - 180 (7.22 + 38.24) months. The complete clearance of feet odor after two weeks of therapy was 35 (70%) patients which was similar to two months maintenance therapy 35 (70%) and was highly statistically significant (p value = 0.0000001). Group B: Fifty patients received the placebo solution, their ages ranged from 16 - 75 (32.6 + 13.4) years, while the duration of the disease ranged from 1 - 180 (43.7 + 47.65) months. The complete clearance of feet odor was in 1 (2%) patient after two weeks therapy and after two months maintenance therapy. No side effects were recorded. Conclusions: Topical 15% zinc sulfate solution had an effective therapeutic and prophylactic action against feet odor.展开更多
Edema is a sign/symptom which has origin diverse causes and mechanisms of installations. I do believe that it can be classified into appendicular and axial edemas with reference to the body division rather than the pr...Edema is a sign/symptom which has origin diverse causes and mechanisms of installations. I do believe that it can be classified into appendicular and axial edemas with reference to the body division rather than the present classification of peripheral edema and other edemas. Edema being a sign/symptom as an entity does cause other signs and symptoms in the body. From observations, I do believe that a cemented floor causes the development of feet edema in specific individuals with genetic predisposition. This can be confirmed by the fact that when these persons place their feet on somewhere else rather than the floor, they do not develop an edema.展开更多
This study proposed a wave power system with two coaxial floating cylinders of different diameters and drafts.Wavebob’s conceptual design has been adopted in the wave power system.In this study,a basic analysis of th...This study proposed a wave power system with two coaxial floating cylinders of different diameters and drafts.Wavebob’s conceptual design has been adopted in the wave power system.In this study,a basic analysis of the wave energy extraction by the relative motion between two floats is presented.The maximum power absorption was studied theoretically under regular wave conditions,and the effects of both linear and constant damping forces on the power take-off(PTO)were investigated.A set of dynamic equations describing the floats’displacement under regular waves and different PTOs are established.A time-domain numerical model is developed,considering the PTO parameter and viscous damping,and the optimal PTO damping and output power are obtained.With the analysis of estimating the maximum power absorption,a new estimation method called Power Capture Function(PCF)is proposed and constructed,which can be used to predict the power capture under both linear and constant PTO forces.Based on this,energy extraction is analyzed and optimized.Finally,the performance characteristics of the two-body power system are concluded.展开更多
The objective of this study was characterizing the gelatin from the chicken feet by FTIR (Fourier transform infrared) spectroscopy. Two gelatin samples were prepared for the experiment which were extracted of 200 g ...The objective of this study was characterizing the gelatin from the chicken feet by FTIR (Fourier transform infrared) spectroscopy. Two gelatin samples were prepared for the experiment which were extracted of 200 g of chicken feet by a thermal bath of 4% acetyl acid solution at 60 ℃. A commercial gelatin was used to compare the results. FTIR spectra of gelatin samples were recorded using a Nicolet iS5 FTIR spectrometer equipped with an ATR/iD3 with argon horizontal cell in which the spectra were varied in the range of 400-4,000 cm1 at 16 ~C. The results showed that FTIR spectra of the chicken feet gelatin had the most with the vibration peak at wave numbers of 1,652.01 cm~ to the amide I, of 1,539.87 cm1 to the amide II, of 1,241.29 cm~ to the amide III, of 2,923.72 cm-~ to the amide B and of 3,399.56 cm~ to the amide A. The collagen composition of the chicken feet gelatins was twotimes larger than the commercial gelatin and the vibration bands to beef gelatin have been different from chicken feet gelatins. This demonstrates that chicken feet gelatins are very good nutritional quality when compared to the commercial gelatin.展开更多
Climate change (CC) and variability have been world widely reported to pose number of risks in aviation industry including accidents, astray, and other operational difficulties. The impact of weather on landing and ta...Climate change (CC) and variability have been world widely reported to pose number of risks in aviation industry including accidents, astray, and other operational difficulties. The impact of weather on landing and take-off performances has been several times experienced at Abeid Amani Karume International Airport (AAKIA);however, the influence of climate change and variability to the aircraft performance needs to be assessed. Thus, this study investigated the influence of climate change and variability on aircrafts take-off and landing performances. Specifically, the study investigated;i) the influence of climate change on Take-off Distance Required (TODR) and Maximum Take-off Mass (MTOM) for different types of aircraft;ii) the influence of climate variability to the aircraft landing performance on light, medium and heavy aircraft and lastly, iii) the study investigated the seasonal and annual variability on aircraft landing performance due to climate variability. The datasets used in this study include the eight years (2014-2021), aircraft operational records (diversion and missed approach events) and Aviation Routine Weather Reports (METAR) records which were utilized as the indicators for landing performance, the long-term (1990-2020) annual maximum temperatures (Tmax) which was used to determine the TODR and MTOM. Statistical tools including mean, percentage changes, correlations, regression, and the chi-square test were used for analysis and hypotheses testing. The results revealed that light and medium aircraft categories were significantly most affected on diversion events as compared to the heavy categories;however, for the missed approach events the impact was vice versa. Moreover, the seasonal and annual variability on diversion and missed approach events were significantly different (at p ≤ 0.001). As for the take-off performance, results show that the TODR and MTOM were significantly increasing and decreasing (at p ≤ 0.001), based on increasing air temperatures. Therefore, the study concludes that the changing climate has significantly affected aircraft by increasing the TODR and decreasing the MTOM, while the climate variability has significantly affected landing performance by influencing the diversion and missed approach events. Thus, the study recommends (i) further research works including the feasibility study on runway extension for the safety of future aircraft operations at the AAKIA and (ii) proper maintenance and improvement of the Instrumental Landing Systems (ILS) as an adaptation measures to the landing aircraft during bad weather events.展开更多
The two waves period of the COVID-19 pandemic saw the use of hydro- alcoholic gel and the consumption of capsules containing improved traditional remedies. At one point, there was a stock-out and a price increase...The two waves period of the COVID-19 pandemic saw the use of hydro- alcoholic gel and the consumption of capsules containing improved traditional remedies. At one point, there was a stock-out and a price increase forthese products. Furthermore, in the food industry, the catering industry adopts gelatin in its current practice. Pig gelatin dominates the international market. And for some religious practices, pork is forbidden and yet these people consume them without taking notice. The production of gelatin from broiler feet seems economically viable because broiler feet are considered slaughterhouse waste that is sold at very low prices. The poultry industry has seen an increase in broiler farming over the last twenty years. However, the latter has all the characteristics required for the production of gelatin. It will therefore comply with the standards of use described in the international codex oenological for gelatins. Physical and chemical analyses such as, ash content, moisture content, and pH measurements were done for the extracted gelatins. Sensible elements are checked with ED XRF spectroscopy. All the results were good and showed without any doubt that broiler gelatin is edible.展开更多
文摘Young Tom is four years old.He is bright(聪明的)and lovely(可爱的).His father and mother lovehim very much.His father works ina factory.He always has a lot ofwork to do.So his mother oftenfeeds(喂)him food and carrieshim in her arms.Tom is too pam-pered(娇惯的).
文摘A general mathematical model of carrier-based aircraft ski jump take-off is derived based on tensor. The carrier, the aircraft body and the movable parts of the landing gears are treated as independent entities. These entities are assembled into a multi-rigid-body system with flexible links. Dynamical equations of each entity are derived on the basis of the Newton law and the Euler transformation. Using the invariance property of the tensor, the dynamical and kinematical equations are converted to tensor forms which are invariant under time-dependent coordinate transformations. Then the tensor-formed equations are expressed by the matrix operation. Differential equation group of the matrix form is formulated for the programming. The closure of the model is discussed, and the simulation results are given.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.51205346 and 41206074)the National High Technology Research and Development Program of China(863 Program+3 种基金Grant No.2011AA050201)Science Fund for Creative Research Groups of National Natural Science Foundation of China(Grant No.51221004)Zhejiang Provincial Natural Science Foundation of China(Grant No.LY12E05017)Open Foundation of the State Key Laboratory of Fluid Power Transmission and Control(Grant No.GZKF-201311)
文摘This paper describes a dual-stroke acting hydraulic power take-off (PTO) system employed in the wave energy converter (WEC) with an inverse pendulum. The hydraulic PTO converts slow irregular reciprocating wave motions to relatively smooth, fast rotation of an electrical generator. The design of the hydraulic PTO system and its control are critical to maximize the generated power. A time domain simulation study and the laboratory experiment of the full-scale beach test are presented. The results of the simulation and laboratory experiments including their comparison at full-scale are also presented, which have validated the rationality of the design and the reliability of some key components of the prototype of the WEC with an inverse pendulum with the dual-stroke acting hydraulic PTO system.
基金financially supported by the Shandong Provincial Natural Science Key Basic Program(Grant No.ZR2017ZA0202)the Qingdao Municipal Science&Technology Program(Grant No.15-8-3-7-jch)Special Project for Marine Renewable Energy(Grant No.GHME2016YY02)
文摘Among the wave energy converters (WECs), oscillating buoy is a promising type for wave energy development in offshore area. Conventional single-freedom oscillating buoy WECs with linear power take-off (PTO) system are less efficient under off-resonance conditions and have a narrow power capture bandwidth. Thus, a multi-freedom WEC with a nonlinear PTO system is proposed. This study examines a multi-freedom WEC with 3 degrees of freedom: surge, heave and pitch. Three different PTO systems (velocity-square, snap through, and constant PTO systems) and a traditional linear PTO system are applied to the WEC. A time-domain model is established using linear potential theory and Cummins equation. The kinematic equation is numerically calculated with the fourth-order Runge–Kutta method. The optimal average output power of the PTO systems in all degrees of freedom are obtained and compared. Other parameters of snap through PTO are also discussed in detail. Results show that according to the power capture performance, the order of the PTO systems from the best to worst is snap through PTO, constant PTO, linear PTO and velocity-square PTO. The resonant frequency of the WEC can be adjusted to the incident wave frequency by choosing specific parameters of the snap through PTO. Adding more DOFs can make the WEC get a better power performance in more wave frequencies. Both the above two methods can raise the WEC’s power capture performance significantly.
文摘A novel method for estimating the space range of battery-powered vertical take-off and landing(VTOL) aircraft is presented. The method is based on flight parameter optimization and numerical iteration. Subsystem models including required thrust, required power and battery discharge models are presented. The problem to be optimized is formulated, and then case study simulation is conducted using the established method for quantitative analysis. Simulation results show that the space range of battery-powered VTOL aircraft in a vertical plane is an oblate curve, which appears horizontally long but vertically short, and the peak point is not located on the vertical climb path. The method and results are confirmed by parameter analysis and validations.
基金financially supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA13040202)the Special Funding Program for Marine Renewable Energy of the State Oceanic Administration(Grant No.GHME2017SF01)
文摘The " Sharp Eagle” device is a wave energy converter of a hinged double floating body. The wave-absorbing floating body hinges on the semi-submerged floating body structure. Under the action of wave, the wave-absorbing floating body rotates around the hinge point, and the wave energy can be converted into kinetic energy. In this paper, the power take-off system of " Sharp Eagle Ⅱ” wave energy converter (the second generation of " Sharp Eagle”) was studied, which adopts the hydraulic type power take-off system. The 0-1 power generation mode was applied in this system to make the " Sharp Eagle Ⅱ” operate under various wave conditions. The principle of power generation was introduced in detail, and the power take-off system was simulated. Three groups of different movement period inputs were used to simulate three kinds of wave conditions, and the simulation results were obtained under three different working conditions. In addition, the prototype of " Sharp Eagle Ⅱ” wave energy converter was tested on land and in real sea conditions. The experimental data have been collected, and the experimental data and simulation results were compared and validated. This work has laid a foundation for the design and application of the following " Sharp Eagle” series of devices.
文摘Nowadays, the success of the new technology development and deployment process depends not only on technical, technological solutions, but also on solving the non-technological problems and crossing the societal and psychological barriers. A large international European projects, GABRIEL1 had developed a maglev assisted aircraft take-off and landing, that was applied to conceptual design of aircraft and required on-board and ground systems, had analysed all impacts (effects of concept deployment on effectiveness, safety, security, noise, emissions) and had demonstrated the safe applicability by concept validation. The applied methodology, used methods and the results of the Gabriel projects had been described and discussed by 55 project deliverables. This paper has a special goal: investigating the problems and barriers of possible implementing of the radically new technology, aircraft MagLev assisted take-off and landing. The study was started by identification and classification of the problems and barriers. After it, the problems were systematically analysed by use of special methodology containing the understanding (description) of the problems, investigation of the possible solutions and discussing their applicability (mainly by use of the Gabriel project results). The paper has three major sections: 1) description of the Gabriel concept and project results, 2) introducing some related thoughts on general aspects of new technology developments, and 3) discussion on the problems and their solutions. The major classes of the problems are the 1) technical, technological problems as developing a radically new solution, landing the undercarriage-less aircraft on the magnetic tracks, 2) stakeholders’ problems as decision makers kicking against supporting the developments of so radically new technologies and 3) society barriers like society worrying on and fear of future passengers on flying by aircraft have not conventional undercarriage systems. The paper will show that these problems have safe and cost-effective solutions.
基金supported by the National Natural Science Foundation of China (61005082, 61020106005)Doctoral Fund of Ministry of Education of China (20100001120005)+1 种基金PKU-Biomedical Engineering Join Seed Grant 2012the 985 Project of PekingUniversity (3J0865600)
文摘Passive dynamic walking has been developed as a possible explanation for the efficiency of the human gait. This paper presents a passive dynamic walking model with segmented feet, which makes the bipedal walking gait more close to natural human-like gait. The proposed model extends the simplest walking model with the addition of fiat feet and torsional spring based compliance on ankle joints and toe joints, to achieve stable walking on a slope driven by gravity. The push-off phase includes foot rotations around the toe joint and around the toe tip, which shows a great resemblance to human normal walking. This paper investigates the effects of the segmented foot structure on bipedal walking in simulations. The model achieves satisfactory walking results on even or uneven slopes.
基金Project(51221004)supported by the Science Fund for Creative Research Groups of National Natural Science Foundation of ChinaProject supported by the Program for Zhejiang Leading Team of S&T Innovation,China
文摘The semi-round rigid feet would cause position-posture deviation problem because the actual foothold position is hardly known due to the rolling effect of the semi-round rigid feet during the robot walking. The position-posture deviation problem may harm to the stability and the harmony of the robot, or even makes the robot tip over and fail to walk forward. Focused on the position-posture deviation problem of multi-legged walking robots with semi-round rigid feet, a new method of position-posture closed-loop control is proposed to solve the position-posture deviation problem caused by semi-round rigid feet, based on the inverse velocity kinematics of the multi-legged walking robots. The position-posture closed-loop control is divided into two parts: the position closed-loop control and the posture closed-loop control. Thus, the position-posture control for the robot which is a tight coupling and nonlinear system is decoupled. Co-simulations of position-posture open-loop control and position-posture closed-loop control by MATLAB and ADAMS are implemented, respectively. The co-simulation results verify that the position-posture closed-loop control performs well in solving the position-posture deviation problem caused by semi-round rigid feet.
文摘While injuries of the upper extremity are widely discussed in rock climbers, reports about the lower extremity are rare. Nevertheless almost 50 percent of acute injuries involve the leg and feet. Acute injuries are either caused by ground falls or rock hit trauma during a fall. Most frequently strains, contusions and fractures of the calcaneus and talus. More rare injuries, as e.g., osteochondral lesions of the talus demand a highly specialized care and case presentations with combined iliac crest graft and matrix associated autologous chondrocyte transplantation are given in this review. The chronic use of tight climbing shoes leads to overstrain injuries also. As the tight fit of the shoes changes the biomechanics of the foot an increased stress load is applied to the fore-foot. Thus chronic conditions as subungual hematoma, callosity and pain resolve. Also a high incidence of hallux valgus and hallux rigidus is described.
文摘Background: Feet odor is a common sociomedical problem that affects the feet of human beings of different etiological factors. Multiple modalities of therapy have been used in the treatment of feet odor. Objective: To evaluate the efficacy and safety of topical 15% zinc sulfate solution in the treatment of feet odor. Patients and Methods: This single blind, placebo, controlled therapeutic study was conducted at the Department of Dermatology-Baghdad Teaching Hospital, from March 2010 to July 2011. A total of 108 (88 males and 20 females) patients with feet odor were enrolled and were divided into 2 groups: Group A: treated with 15% zinc sulfate solution. Group B: treated with distilled water as placebo control group. Full history and examination were carried out including all relevant points. Four scoring had been used to assess the severity of odor in patients with bared feet Score 0: no odor, Score 1: mild odor, Score 2: moderate odor and Score 3: severe odor. Zinc sulfate solution 15% was applied to sole and toe webs once daily for two weeks, three times per week for next two weeks and followed by single application weekly as maintenance after clearance of odor for two months. Patients were seen every two weeks to be examined and to score the odor again and to record side effects. Results: Group A: Fifty patients completed the study, their ages ranged from 8 - 68 (33 + 14.5) years, while the duration of the disease ranged from 1 - 180 (7.22 + 38.24) months. The complete clearance of feet odor after two weeks of therapy was 35 (70%) patients which was similar to two months maintenance therapy 35 (70%) and was highly statistically significant (p value = 0.0000001). Group B: Fifty patients received the placebo solution, their ages ranged from 16 - 75 (32.6 + 13.4) years, while the duration of the disease ranged from 1 - 180 (43.7 + 47.65) months. The complete clearance of feet odor was in 1 (2%) patient after two weeks therapy and after two months maintenance therapy. No side effects were recorded. Conclusions: Topical 15% zinc sulfate solution had an effective therapeutic and prophylactic action against feet odor.
文摘Edema is a sign/symptom which has origin diverse causes and mechanisms of installations. I do believe that it can be classified into appendicular and axial edemas with reference to the body division rather than the present classification of peripheral edema and other edemas. Edema being a sign/symptom as an entity does cause other signs and symptoms in the body. From observations, I do believe that a cemented floor causes the development of feet edema in specific individuals with genetic predisposition. This can be confirmed by the fact that when these persons place their feet on somewhere else rather than the floor, they do not develop an edema.
基金financially supported by the National Key R&D Program of China (Grant No. 2018YFB1501904)the Shandong Provincial Key R&D Program (Grant No. 2019JZZY010902)+2 种基金the National Natural Science Foundation of China (Grant No. 52071303)the Joint Project of NSFC-SD (Grant No. U1906228)the Taishan Scholars Program of Shandong Province (Grant No. ts20190914)
文摘This study proposed a wave power system with two coaxial floating cylinders of different diameters and drafts.Wavebob’s conceptual design has been adopted in the wave power system.In this study,a basic analysis of the wave energy extraction by the relative motion between two floats is presented.The maximum power absorption was studied theoretically under regular wave conditions,and the effects of both linear and constant damping forces on the power take-off(PTO)were investigated.A set of dynamic equations describing the floats’displacement under regular waves and different PTOs are established.A time-domain numerical model is developed,considering the PTO parameter and viscous damping,and the optimal PTO damping and output power are obtained.With the analysis of estimating the maximum power absorption,a new estimation method called Power Capture Function(PCF)is proposed and constructed,which can be used to predict the power capture under both linear and constant PTO forces.Based on this,energy extraction is analyzed and optimized.Finally,the performance characteristics of the two-body power system are concluded.
文摘The objective of this study was characterizing the gelatin from the chicken feet by FTIR (Fourier transform infrared) spectroscopy. Two gelatin samples were prepared for the experiment which were extracted of 200 g of chicken feet by a thermal bath of 4% acetyl acid solution at 60 ℃. A commercial gelatin was used to compare the results. FTIR spectra of gelatin samples were recorded using a Nicolet iS5 FTIR spectrometer equipped with an ATR/iD3 with argon horizontal cell in which the spectra were varied in the range of 400-4,000 cm1 at 16 ~C. The results showed that FTIR spectra of the chicken feet gelatin had the most with the vibration peak at wave numbers of 1,652.01 cm~ to the amide I, of 1,539.87 cm1 to the amide II, of 1,241.29 cm~ to the amide III, of 2,923.72 cm-~ to the amide B and of 3,399.56 cm~ to the amide A. The collagen composition of the chicken feet gelatins was twotimes larger than the commercial gelatin and the vibration bands to beef gelatin have been different from chicken feet gelatins. This demonstrates that chicken feet gelatins are very good nutritional quality when compared to the commercial gelatin.
文摘Climate change (CC) and variability have been world widely reported to pose number of risks in aviation industry including accidents, astray, and other operational difficulties. The impact of weather on landing and take-off performances has been several times experienced at Abeid Amani Karume International Airport (AAKIA);however, the influence of climate change and variability to the aircraft performance needs to be assessed. Thus, this study investigated the influence of climate change and variability on aircrafts take-off and landing performances. Specifically, the study investigated;i) the influence of climate change on Take-off Distance Required (TODR) and Maximum Take-off Mass (MTOM) for different types of aircraft;ii) the influence of climate variability to the aircraft landing performance on light, medium and heavy aircraft and lastly, iii) the study investigated the seasonal and annual variability on aircraft landing performance due to climate variability. The datasets used in this study include the eight years (2014-2021), aircraft operational records (diversion and missed approach events) and Aviation Routine Weather Reports (METAR) records which were utilized as the indicators for landing performance, the long-term (1990-2020) annual maximum temperatures (Tmax) which was used to determine the TODR and MTOM. Statistical tools including mean, percentage changes, correlations, regression, and the chi-square test were used for analysis and hypotheses testing. The results revealed that light and medium aircraft categories were significantly most affected on diversion events as compared to the heavy categories;however, for the missed approach events the impact was vice versa. Moreover, the seasonal and annual variability on diversion and missed approach events were significantly different (at p ≤ 0.001). As for the take-off performance, results show that the TODR and MTOM were significantly increasing and decreasing (at p ≤ 0.001), based on increasing air temperatures. Therefore, the study concludes that the changing climate has significantly affected aircraft by increasing the TODR and decreasing the MTOM, while the climate variability has significantly affected landing performance by influencing the diversion and missed approach events. Thus, the study recommends (i) further research works including the feasibility study on runway extension for the safety of future aircraft operations at the AAKIA and (ii) proper maintenance and improvement of the Instrumental Landing Systems (ILS) as an adaptation measures to the landing aircraft during bad weather events.
文摘The two waves period of the COVID-19 pandemic saw the use of hydro- alcoholic gel and the consumption of capsules containing improved traditional remedies. At one point, there was a stock-out and a price increase forthese products. Furthermore, in the food industry, the catering industry adopts gelatin in its current practice. Pig gelatin dominates the international market. And for some religious practices, pork is forbidden and yet these people consume them without taking notice. The production of gelatin from broiler feet seems economically viable because broiler feet are considered slaughterhouse waste that is sold at very low prices. The poultry industry has seen an increase in broiler farming over the last twenty years. However, the latter has all the characteristics required for the production of gelatin. It will therefore comply with the standards of use described in the international codex oenological for gelatins. Physical and chemical analyses such as, ash content, moisture content, and pH measurements were done for the extracted gelatins. Sensible elements are checked with ED XRF spectroscopy. All the results were good and showed without any doubt that broiler gelatin is edible.