When a cluster of unmanned aerial vehicles (UAVs) is flying in formation, it is crucial to maintain the formation and not to be interfered by external electromagnetic wave signals. In order to maintain the formation, ...When a cluster of unmanned aerial vehicles (UAVs) is flying in formation, it is crucial to maintain the formation and not to be interfered by external electromagnetic wave signals. In order to maintain the formation, this paper proposes to use pure azimuth passive positioning to adjust the position of UAVs, i.e., certain UAVs in the formation transmit signals, the rest of the UAVs receive the signals passively, and extract the orientation information from them to adjust the position of the UAVs [1] [2] [3]. In this paper, the position adjustment problem of UAVs in “circular” formation flight under three models is investigated. To address the problem of “how to obtain the position of the receiving UAV when there are two UAVs with known numbers and evenly distributed on the circumference in addition to the UAV transmitting at the known center of the circle, and the rest of the UAVs with slight deviations in their positions are receiving the signals”, two purely mathematical geometric methods, namely, triangular localization method and polar co-ordinate method, are proposed respectively. We have determined the position of the receiving UAV;we have used the exhaustive method and the construction and disproof method to solve the problem of “how many UAVs are needed to transmit signals in order to realize the effective positioning of the UAVs when it is known that a certain UAV with a slight deviation in its position receives the signals emitted by two UAVs at the same time”, and the results show that: in addition to the known signals emitted by two UAVs, it is also necessary to transmit the signals emitted by two UAVs. The results show that in addition to the known two UAVs transmitting signals, two additional UAVs are required to transmit signals for precise po-sitioning. When the position of UAVs has deviation at the initial moment, the ideal approximation method and the target delimitation method are pro-posed, and the target of nine UAVs uniformly distributed on a circle of a spe-cific radius is achieved through several adjustments, after which the ad-vantages and disadvantages of each model are analyzed, and suggestions for improvement are put forward. The purely azimuthal passive localization method and the constructed model approach proposed in this paper can be extended to other fields, such as spacecraft formations in space and battle-ship formations at sea, as well as other formation flight position adjustment problems.展开更多
Objectives: Sex work is not well documented among African men. The aim of this study was to describe the epidemiological profile of men who have sex with men (MSM) and eventually to determine the proportion of sex wor...Objectives: Sex work is not well documented among African men. The aim of this study was to describe the epidemiological profile of men who have sex with men (MSM) and eventually to determine the proportion of sex workers (SW) among them, as well as the proportion of MSM who have been victims of gender-based violence (GBV). Material and Methods: A cross-sectional study coordinated by the Direction de la Médecine du Travail was carried out at the headquarters of the association ALTERNATIVES in Bangui Bangui from July 1 to October 31, 2021. Consenting MSM present during the study period were systematically included. Sociodemographic variables, those relating to the future vision of the activity and to GBV were collected and analyzed using Epi-Info version 7 software. Results: Forty MSM with an average age of 23 years and mainly secondary education (75.0%) were included. The vast majority of MSM were unemployed (85.0%). 45.0% had been victims of GBV and wanted to stop working as an MSM (47.5%), and almost 2/3 (65.0%) would accept another income-generating activity in exchange for the MSM. Violence was sexual (32.5%), economic (22.5%), physical (20.0%), verbal (12.5%) and psychological (12.5%). Conclusion: The MSM were mainly young, poorly educated, unemployed, and almost half were victims of GBV. The desire to change MSM activity to another income-generating activity alongside that of MSM shows that many of them are SW, workers in the informal sector. This must be taken into account in prevention activities, even if the data needs to be confirmed on a much larger sample.展开更多
Electric vehicles use electric motors, which turn electrical energy into mechanical energy. As electric motors are conventionally used in all the industry, it is an established development site. It’s a mature technol...Electric vehicles use electric motors, which turn electrical energy into mechanical energy. As electric motors are conventionally used in all the industry, it is an established development site. It’s a mature technology with ideal power and torque curves for vehicular operation. Conventional vehicles use oil and gas as fuel or energy storage. Although they also have an excellent economic impact, the continuous use of oil and gas threatened the world’s reservation of total oil and gas. Also, they emit carbon dioxide and some toxic ingredients through the vehicle’s tailpipe, which causes the greenhouse effect and seriously impacts the environment. So, as an alternative, electric car refers to a green technology of decarbonization with zero emission of greenhouse gases through the tailpipe. So, they can remove the problem of greenhouse gas emissions and solve the world’s remaining non-renewable energy storage problem. Pure electric vehicles (PEV) can be applied in all spheres, but their special implementation can only be seen in downhole operations. They are used for low noise and less pollution in the downhole process. In this study, the basic structure of the pure electric command vehicle is studied, the main components of the command vehicle power system, namely the selection of the drive motor and the power battery, are analyzed, and the main parameters of the drive motor and the power battery are designed and calculated. The checking calculation results show that the power and transmission system developed in this paper meets the design requirements, and the design scheme is feasible and reasonable.展开更多
Introduction: Urethroplasty remains the gold standard for the management of urethral stricture. However, the treatment of stricture disease in the elderly tends to be less invasive due to the presumption that they mig...Introduction: Urethroplasty remains the gold standard for the management of urethral stricture. However, the treatment of stricture disease in the elderly tends to be less invasive due to the presumption that they might not be able to stand long hours of surgery and might have higher rates of recurrence due to poor wound healing from microangiopathy. We present our experience with the outcomes of urethroplasty among elderly men seen at the Komfo Anokye Teaching Hospital from January 2012 to December 2021. Methods: This was a retrospective review of data captured in the urology database on all patients 65 years and above who underwent urethroplasty at the hospital over the study period. Data was obtained on patients’ demographics, stricture characteristics, urethroplasty technique, and outcome. A successful outcome was defined as peak flow rate > 15 mls/s, a patent urethra on retrograde urethrogram, patient satisfaction with urine stream, or restoration of the normal stream of urine with only one attempt at urethral calibration or internal urethrotomy postoperatively. Data was analyzed using PASW Statistics for Windows, Version 18.0. Results: Overall, 43 urethroplasties were done over the study period in elderly men. The age range was 65 to 87 years. The commonest aetiology was catheterization (62.79%) followed by urethritis (32.56%). Stricture length ranged from 0.5 cm to 16 cm with a mean of 3.93 cm. Most patients (60.46%) had bulbar urethral strictures. The repair methods employed were anastomotic urethroplasty (62.80%), fasciocutaneous flap (FCF) ventral onlay (13.95%), buccal mucosa graft (BMG) ventral onlay urethroplasty (4.65%), and staged urethroplasty (4.65%). Three of the patients (6.98%) had a combination of anastomotic and tissue transfer urethroplasty. The overall success rate was 88.37%. Complications included three surgical site infections, two urethral diverticula and one glans dehiscence. Conclusion: Elderly men tolerate urethroplasty well and the procedure should not be denied solely based on age.展开更多
Electrocatalytic reduction of CO_(2) converts intermittent renewable electricity into value-added liquid products with an enticing prospect,but its practical application is hampered due to the lack of high-performance...Electrocatalytic reduction of CO_(2) converts intermittent renewable electricity into value-added liquid products with an enticing prospect,but its practical application is hampered due to the lack of high-performance electrocatalysts.Herein,we elaborately design and develop strongly coupled nanosheets composed of Ag nanoparticles and Sn-SnO_(2) grains,designated as Ag/Sn-SnO_(2) nanosheets(NSs),which possess optimized electronic structure,high electrical conductivity,and more accessible sites.As a result,such a catalyst exhibits unprecedented catalytic performance toward CO_(2)-to-formate conversion with near-unity faradaic efficiency(≥90%),ultrahigh partial current density(2,000 mA cm^(−2)),and superior long-term stability(200 mA cm^(−2),200 h),surpassing the reported catalysts of CO_(2) electroreduction to formate.Additionally,in situ attenuated total reflection-infrared spectra combined with theoretical calculations revealed that electron-enriched Sn sites on Ag/Sn-SnO_(2)NSs not only promote the formation of*OCHO and alleviate the energy barriers of*OCHO to*HCOOH,but also impede the desorption of H*.Notably,the Ag/Sn-SnO_(2)NSs as the cathode in a membrane electrode assembly with porous solid electrolyte layer reactor can continuously produce~0.12 M pure HCOOH solution at 100 mA cm^(−2)over 200 h.This work may inspire further development of advanced electrocatalysts and innovative device systems for promoting practical application of producing liquid fuels from CO_(2).展开更多
The dynamic system control circuit board(DSCCB)is one of the most important components for dynamic system of pure electric vehicles. The current detection of the DSCCB is done manually, which is not only inefficient i...The dynamic system control circuit board(DSCCB)is one of the most important components for dynamic system of pure electric vehicles. The current detection of the DSCCB is done manually, which is not only inefficient in the detection but also difficult to guarantee the data accuracy. In order to improve the detection efficiency and accuracy, a new testing system is designed by Labview. The total test time can be further reduced by about 75% compared with the results of the manual detection. In this paper, the three-parameter sine wave curve-fit algorithm theory is applied to the phase delay detection of the current sensor sampling circuit on the DSCCB. This method solves the problem of big error in the phase delay detection.展开更多
The equal channel angular pressing(ECAP)experiments were carried out with industrial pure aluminum and an in-house mould.The comparison of material grain size before and after ECAP was performed by applying the techni...The equal channel angular pressing(ECAP)experiments were carried out with industrial pure aluminum and an in-house mould.The comparison of material grain size before and after ECAP was performed by applying the technique of electron back scattered diffraction(EBSD).The results show that the grains in the material after ECAP are refined and the yield stress and ultimate strength are increased.In order to investigate the deformation mechanism during ECAP and the reason for driving grain size refinement,three-dimensional numerical simulations of the ECAP process were carried out.Based on the Lode parameter analysis, the deformation of the material sample is found very complicated,not just pure shear during extrusion through the angular channel. The simulation confirms that a strong strain gradient in the sample material is imposed by the ECAP.展开更多
We utilize two different theories to prove that cosmic dark energy density is the complimentary Legendre transformation of ordinary energy and vice versa as given by E(dark) = mc2 (21/22) and E(ordinary) = mc2/22. The...We utilize two different theories to prove that cosmic dark energy density is the complimentary Legendre transformation of ordinary energy and vice versa as given by E(dark) = mc2 (21/22) and E(ordinary) = mc2/22. The first theory used is based on G ‘t Hooft’s remarkably simple renormalization procedure in which a neat mathematical maneuver is introduced via the dimensionality of our four dimensional spacetime. Thus, ‘t Hooft used instead of D = 4 and then took at the end of an intricate and subtle computation the limit to obtain the result while avoiding various problems including the pole singularity at D = 4. Here and in contradistinction to the classical form of dimensional and renormalization we set and do not take the limit where and is the theoretically and experimentally well established Hardy’s generic quantum entanglement. At the end we see that the dark energy density is simply the ratio of and the smooth disentangled D = 4, i.e. (dark) = (4 -k)/4 = 3.8196011/4 = 0.9549150275. Consequently where we have ignored the fine structure details by rounding 21 + k to 21 and 22 + k to 22 in a manner not that much different from of the original form of dimensional regularization theory. The result is subsequently validated by another equally ingenious approach due mainly to E. Witten and his school of topological quantum field theory. We notice that in that theory the local degrees of freedom are zero. Therefore, we are dealing essentially with pure gravity where are the degrees of freedom and is the corresponding dimension. The results and the conclusion of the paper are summarized in Figure 1-3, Table 1 and Flow Chart 1.展开更多
It was shown by TEM and X-ray analysis that there are four types of grains of the main Ni3Al phase in the structure of the intermetallic obtained by the self-propagation high temperature method (SHS). Every type of gr...It was shown by TEM and X-ray analysis that there are four types of grains of the main Ni3Al phase in the structure of the intermetallic obtained by the self-propagation high temperature method (SHS). Every type of grains has its own domain and dislocation structure. There are mono- and polydomains with and without dislocations. The grains of the main phase of monoand polydomains without dislocations and polydomains with dislocations were formed by diffusion in the solid phase. In these conditions NiAl3 phase is located on the grain boundary of the main phase. The Ni2Al3 phase is located at the triple joints of the main phase.展开更多
Asymmetric rolling(ASR), as one of severe plastic deformation(SPD) methods, was widely used to make ultra-fined materials with enhanced performance. Internal marks were used to show the shear deformation during asymme...Asymmetric rolling(ASR), as one of severe plastic deformation(SPD) methods, was widely used to make ultra-fined materials with enhanced performance. Internal marks were used to show the shear deformation during asymmetric rolling with pure aluminium as a model material. Effects of reduction ratio and mismatch ratio on the shear deformation were studied. With the observed shear deformation results, equivalent strain was calculated. For lager shear deformation, rolling equipment was modified to increase friction between specimen and the rollers. Consequently, extremely fine grains with size of 500 nm are obtained in pure aluminium. With improved asymmetric rolling, the ability of grain refinement of ASR is greatly improved.展开更多
MANY cases of pure red cell aplasia(PRCA)were mediated by over-function of immune cells,and responded well to immunosuppressive therapy.1 Sometimes refractory cases also arose.Fludarabine is an analogue of adenosine r...MANY cases of pure red cell aplasia(PRCA)were mediated by over-function of immune cells,and responded well to immunosuppressive therapy.1 Sometimes refractory cases also arose.Fludarabine is an analogue of adenosine resistant to deamination which is widely used for B-chronic lymphocytic leukemia(CLL)and other hematological malignancies.2 As a strong immunosuppressive agent,展开更多
With the wide acceptance of the computing concept of cluster-based or cluster-of-clusters computing, network-based high performance computing is gaining increasing popularity among parallel computing community. Curren...With the wide acceptance of the computing concept of cluster-based or cluster-of-clusters computing, network-based high performance computing is gaining increasing popularity among parallel computing community. Current parallel environments such as MPI (Message Passing Interface) or BSP (Bulk Synchronous Parallel) can not apply readily to heterogeneous computing platform. In order to exploit the maximum performance potential that a heterogeneous environment brings, we have made some experiments on implementing BSP in pure Java, a fully platform-independent language. The experimental results show that implementation of parallel libraries in Java is feasible and the performance is moderately acceptable. The paper describes our experiences in implementation of BSP in pure Java. Implementation and efficiency issues such as data transport, network communication, support thread, barrier synchronization and dynamic class loading mechanism are discussed in detail.展开更多
The Ni3B phase was formed when boron (0.5 at. pct B) was added to the intermetallic of sto- ichiometric and off-stoichiometric (Ni-24 at. pct Al) compounds. In the alloy of stoichiometric composition the particles...The Ni3B phase was formed when boron (0.5 at. pct B) was added to the intermetallic of sto- ichiometric and off-stoichiometric (Ni-24 at. pct Al) compounds. In the alloy of stoichiometric composition the particles of Ni3B phase has the size around 0.1μm and is located on the grain boundary of the main phase. The decreasing of concentrations of Al in the ofF-stoichiometric alloy leads to increase in the degree of the long-range order parameter, increasing the concen- trations of boron in the solid solution and decreasing its localization on the grain boundary. Microalloying of boron leads to increasing in the fraction of grain monodomains with disloca- tions up to 0.7 in the alloy of the off-stoichiometric composition and up to 1 in the alloy of the stoichiometric composition. It was established the correlation between the degree of the concentration inhomogeneity, average density of the dislocations and the average long range-order parameter.展开更多
A 2-D numerical model was developed to predict the shape of weld pool in stationary GTA welding of commercial pure aluminium,without considering fluid flow in the weld pool.A Gaussian current density and heat input di...A 2-D numerical model was developed to predict the shape of weld pool in stationary GTA welding of commercial pure aluminium,without considering fluid flow in the weld pool.A Gaussian current density and heat input distribution on the surface of the workpiece were considered.The parameters of Gaussian distribution were modified by comparing calculated results with experimental ones.It was found that these distribution parameters are functions of applied current and arc length.Effects of arc length,applied current and welding time on the geometry of the weld pool were investigated.To check the validity of the model,a series of experiments were also conducted.In general,the agreement between calculated overall shape of the weld pool and the experimental one was acceptable,especially in low applied currents.Therefore,it can be concluded that in pure aluminium,the heat conduction is dominant mechanism of heat transfer in the weld pool.展开更多
The corrosion resistance of pure magnesium with surface alloying layer obtained by a solid diffusion alloying technique has been analyzed. To establish the optimum treatment time, the experiments were performed at 480...The corrosion resistance of pure magnesium with surface alloying layer obtained by a solid diffusion alloying technique has been analyzed. To establish the optimum treatment time, the experiments were performed at 480℃ for different solid diffusion time (8, 16, and 24h). The diffusion interaction effectiveness between Zn, Al mix powder and the sample surface, depending on the treatment time for diffusion at given temperatures, has an obvious influence on corrosion resistance and corrosion mechanism. Corrosion properties were studied using the constant immersion test (in 3.0% NaCl solution, temperature is (28±1)℃, and time is 96h). Optical microscopy (OM) and EDS (energy dispersive spectrum) composition analysis were used to examine the cross-sectional microstructural characteristics of alloyed layer of treated samples. It is shown that in comparison with the untreated samples, the treated ones possess a better corrosion resistance. The Al5Mg11Zn4 phase, which formed as a continuous phase due to the diffusion of Al, Zn, and Mg elements and subsequent interaction on the outermost layer of diffusion alloying zones (especially the samples treated for 24h at 480℃), was inert to the chloride solution compared with pure magnesium and acted as a corrosion barrier, and therefore the best corrosion resistance was obtained. This protective action of A_(l5)Mg_(11)Zn_4 phase was found to change with its amount, which was controlled by the diffusion time at given temperature. It was concluded that the continuous A_(l5)Mg_(11)Zn_4 phase (WP-zone) of the reacted layer in pure magnesium was beneficial from the point of view of corrosion resistance.展开更多
Ultra pure ferritic stainless steel has more advantages in the performance than the ordinary ferritic stainless steel because of ultra low carbon and nitrogen content,such as corrosion resistance,toughness and weldabi...Ultra pure ferritic stainless steel has more advantages in the performance than the ordinary ferritic stainless steel because of ultra low carbon and nitrogen content,such as corrosion resistance,toughness and weldability,etc.Such steel has therefore been applied in many fields,leading to the very rapid development over the past 40 years.This study focuses on the secondary refining process which is the most important step of the whole steelmaking process for the ultra pure ferritic stainless.Firstly,some difficulties of the secondary refining process are described,including the high purification in terms of both carbon and nitrogen contents, high efficient and stable control.Secondly,the development and progress of the secondary refining technology for ultra pure ferritic stainless is introduced in terms of the refining equipments,metallurgical process and assistant technologies.Finally,the prospect was made for the development of secondary refining process for ultra pure ferritic stainless in the future.展开更多
A new probability measure for the quantification of entanglement of pure states is introduced.Numerical computations indicate that the derived measure is equal to concurrence,up to the precision of the computer progra...A new probability measure for the quantification of entanglement of pure states is introduced.Numerical computations indicate that the derived measure is equal to concurrence,up to the precision of the computer program used.Hence it also provides a physical interpretation for concurrence.展开更多
文摘When a cluster of unmanned aerial vehicles (UAVs) is flying in formation, it is crucial to maintain the formation and not to be interfered by external electromagnetic wave signals. In order to maintain the formation, this paper proposes to use pure azimuth passive positioning to adjust the position of UAVs, i.e., certain UAVs in the formation transmit signals, the rest of the UAVs receive the signals passively, and extract the orientation information from them to adjust the position of the UAVs [1] [2] [3]. In this paper, the position adjustment problem of UAVs in “circular” formation flight under three models is investigated. To address the problem of “how to obtain the position of the receiving UAV when there are two UAVs with known numbers and evenly distributed on the circumference in addition to the UAV transmitting at the known center of the circle, and the rest of the UAVs with slight deviations in their positions are receiving the signals”, two purely mathematical geometric methods, namely, triangular localization method and polar co-ordinate method, are proposed respectively. We have determined the position of the receiving UAV;we have used the exhaustive method and the construction and disproof method to solve the problem of “how many UAVs are needed to transmit signals in order to realize the effective positioning of the UAVs when it is known that a certain UAV with a slight deviation in its position receives the signals emitted by two UAVs at the same time”, and the results show that: in addition to the known signals emitted by two UAVs, it is also necessary to transmit the signals emitted by two UAVs. The results show that in addition to the known two UAVs transmitting signals, two additional UAVs are required to transmit signals for precise po-sitioning. When the position of UAVs has deviation at the initial moment, the ideal approximation method and the target delimitation method are pro-posed, and the target of nine UAVs uniformly distributed on a circle of a spe-cific radius is achieved through several adjustments, after which the ad-vantages and disadvantages of each model are analyzed, and suggestions for improvement are put forward. The purely azimuthal passive localization method and the constructed model approach proposed in this paper can be extended to other fields, such as spacecraft formations in space and battle-ship formations at sea, as well as other formation flight position adjustment problems.
文摘Objectives: Sex work is not well documented among African men. The aim of this study was to describe the epidemiological profile of men who have sex with men (MSM) and eventually to determine the proportion of sex workers (SW) among them, as well as the proportion of MSM who have been victims of gender-based violence (GBV). Material and Methods: A cross-sectional study coordinated by the Direction de la Médecine du Travail was carried out at the headquarters of the association ALTERNATIVES in Bangui Bangui from July 1 to October 31, 2021. Consenting MSM present during the study period were systematically included. Sociodemographic variables, those relating to the future vision of the activity and to GBV were collected and analyzed using Epi-Info version 7 software. Results: Forty MSM with an average age of 23 years and mainly secondary education (75.0%) were included. The vast majority of MSM were unemployed (85.0%). 45.0% had been victims of GBV and wanted to stop working as an MSM (47.5%), and almost 2/3 (65.0%) would accept another income-generating activity in exchange for the MSM. Violence was sexual (32.5%), economic (22.5%), physical (20.0%), verbal (12.5%) and psychological (12.5%). Conclusion: The MSM were mainly young, poorly educated, unemployed, and almost half were victims of GBV. The desire to change MSM activity to another income-generating activity alongside that of MSM shows that many of them are SW, workers in the informal sector. This must be taken into account in prevention activities, even if the data needs to be confirmed on a much larger sample.
文摘Electric vehicles use electric motors, which turn electrical energy into mechanical energy. As electric motors are conventionally used in all the industry, it is an established development site. It’s a mature technology with ideal power and torque curves for vehicular operation. Conventional vehicles use oil and gas as fuel or energy storage. Although they also have an excellent economic impact, the continuous use of oil and gas threatened the world’s reservation of total oil and gas. Also, they emit carbon dioxide and some toxic ingredients through the vehicle’s tailpipe, which causes the greenhouse effect and seriously impacts the environment. So, as an alternative, electric car refers to a green technology of decarbonization with zero emission of greenhouse gases through the tailpipe. So, they can remove the problem of greenhouse gas emissions and solve the world’s remaining non-renewable energy storage problem. Pure electric vehicles (PEV) can be applied in all spheres, but their special implementation can only be seen in downhole operations. They are used for low noise and less pollution in the downhole process. In this study, the basic structure of the pure electric command vehicle is studied, the main components of the command vehicle power system, namely the selection of the drive motor and the power battery, are analyzed, and the main parameters of the drive motor and the power battery are designed and calculated. The checking calculation results show that the power and transmission system developed in this paper meets the design requirements, and the design scheme is feasible and reasonable.
文摘Introduction: Urethroplasty remains the gold standard for the management of urethral stricture. However, the treatment of stricture disease in the elderly tends to be less invasive due to the presumption that they might not be able to stand long hours of surgery and might have higher rates of recurrence due to poor wound healing from microangiopathy. We present our experience with the outcomes of urethroplasty among elderly men seen at the Komfo Anokye Teaching Hospital from January 2012 to December 2021. Methods: This was a retrospective review of data captured in the urology database on all patients 65 years and above who underwent urethroplasty at the hospital over the study period. Data was obtained on patients’ demographics, stricture characteristics, urethroplasty technique, and outcome. A successful outcome was defined as peak flow rate > 15 mls/s, a patent urethra on retrograde urethrogram, patient satisfaction with urine stream, or restoration of the normal stream of urine with only one attempt at urethral calibration or internal urethrotomy postoperatively. Data was analyzed using PASW Statistics for Windows, Version 18.0. Results: Overall, 43 urethroplasties were done over the study period in elderly men. The age range was 65 to 87 years. The commonest aetiology was catheterization (62.79%) followed by urethritis (32.56%). Stricture length ranged from 0.5 cm to 16 cm with a mean of 3.93 cm. Most patients (60.46%) had bulbar urethral strictures. The repair methods employed were anastomotic urethroplasty (62.80%), fasciocutaneous flap (FCF) ventral onlay (13.95%), buccal mucosa graft (BMG) ventral onlay urethroplasty (4.65%), and staged urethroplasty (4.65%). Three of the patients (6.98%) had a combination of anastomotic and tissue transfer urethroplasty. The overall success rate was 88.37%. Complications included three surgical site infections, two urethral diverticula and one glans dehiscence. Conclusion: Elderly men tolerate urethroplasty well and the procedure should not be denied solely based on age.
基金the National Science Fund for Distinguished Young Scholars(Grant No.52125103)the National Natural Science Foundation of China(Grant Nos.52301232,52071041,12074048,and 12147102)China Postdoctoral Science Foundation(Grant No.2022M720552).
文摘Electrocatalytic reduction of CO_(2) converts intermittent renewable electricity into value-added liquid products with an enticing prospect,but its practical application is hampered due to the lack of high-performance electrocatalysts.Herein,we elaborately design and develop strongly coupled nanosheets composed of Ag nanoparticles and Sn-SnO_(2) grains,designated as Ag/Sn-SnO_(2) nanosheets(NSs),which possess optimized electronic structure,high electrical conductivity,and more accessible sites.As a result,such a catalyst exhibits unprecedented catalytic performance toward CO_(2)-to-formate conversion with near-unity faradaic efficiency(≥90%),ultrahigh partial current density(2,000 mA cm^(−2)),and superior long-term stability(200 mA cm^(−2),200 h),surpassing the reported catalysts of CO_(2) electroreduction to formate.Additionally,in situ attenuated total reflection-infrared spectra combined with theoretical calculations revealed that electron-enriched Sn sites on Ag/Sn-SnO_(2)NSs not only promote the formation of*OCHO and alleviate the energy barriers of*OCHO to*HCOOH,but also impede the desorption of H*.Notably,the Ag/Sn-SnO_(2)NSs as the cathode in a membrane electrode assembly with porous solid electrolyte layer reactor can continuously produce~0.12 M pure HCOOH solution at 100 mA cm^(−2)over 200 h.This work may inspire further development of advanced electrocatalysts and innovative device systems for promoting practical application of producing liquid fuels from CO_(2).
基金"863"program-saving and new energy vehicles of major projects funded project(2008AA11A154)
文摘The dynamic system control circuit board(DSCCB)is one of the most important components for dynamic system of pure electric vehicles. The current detection of the DSCCB is done manually, which is not only inefficient in the detection but also difficult to guarantee the data accuracy. In order to improve the detection efficiency and accuracy, a new testing system is designed by Labview. The total test time can be further reduced by about 75% compared with the results of the manual detection. In this paper, the three-parameter sine wave curve-fit algorithm theory is applied to the phase delay detection of the current sensor sampling circuit on the DSCCB. This method solves the problem of big error in the phase delay detection.
基金Project(10662001)supported by the National Natural Science Foundation of ChinaProject(0832024)supported by the Natural Science Foundation of Guangxi Province,ChinaProject(2007105930801M39)supported by Graduate Student Education Innovative Program of Guangxi Province,China
文摘The equal channel angular pressing(ECAP)experiments were carried out with industrial pure aluminum and an in-house mould.The comparison of material grain size before and after ECAP was performed by applying the technique of electron back scattered diffraction(EBSD).The results show that the grains in the material after ECAP are refined and the yield stress and ultimate strength are increased.In order to investigate the deformation mechanism during ECAP and the reason for driving grain size refinement,three-dimensional numerical simulations of the ECAP process were carried out.Based on the Lode parameter analysis, the deformation of the material sample is found very complicated,not just pure shear during extrusion through the angular channel. The simulation confirms that a strong strain gradient in the sample material is imposed by the ECAP.
文摘We utilize two different theories to prove that cosmic dark energy density is the complimentary Legendre transformation of ordinary energy and vice versa as given by E(dark) = mc2 (21/22) and E(ordinary) = mc2/22. The first theory used is based on G ‘t Hooft’s remarkably simple renormalization procedure in which a neat mathematical maneuver is introduced via the dimensionality of our four dimensional spacetime. Thus, ‘t Hooft used instead of D = 4 and then took at the end of an intricate and subtle computation the limit to obtain the result while avoiding various problems including the pole singularity at D = 4. Here and in contradistinction to the classical form of dimensional and renormalization we set and do not take the limit where and is the theoretically and experimentally well established Hardy’s generic quantum entanglement. At the end we see that the dark energy density is simply the ratio of and the smooth disentangled D = 4, i.e. (dark) = (4 -k)/4 = 3.8196011/4 = 0.9549150275. Consequently where we have ignored the fine structure details by rounding 21 + k to 21 and 22 + k to 22 in a manner not that much different from of the original form of dimensional regularization theory. The result is subsequently validated by another equally ingenious approach due mainly to E. Witten and his school of topological quantum field theory. We notice that in that theory the local degrees of freedom are zero. Therefore, we are dealing essentially with pure gravity where are the degrees of freedom and is the corresponding dimension. The results and the conclusion of the paper are summarized in Figure 1-3, Table 1 and Flow Chart 1.
文摘It was shown by TEM and X-ray analysis that there are four types of grains of the main Ni3Al phase in the structure of the intermetallic obtained by the self-propagation high temperature method (SHS). Every type of grains has its own domain and dislocation structure. There are mono- and polydomains with and without dislocations. The grains of the main phase of monoand polydomains without dislocations and polydomains with dislocations were formed by diffusion in the solid phase. In these conditions NiAl3 phase is located on the grain boundary of the main phase. The Ni2Al3 phase is located at the triple joints of the main phase.
基金Project(5067062) supported by the National Natural Science Foundation of ChinaProject(NCET-04-0386) supported by New Century Scholarship of the Ministry of Education of China
文摘Asymmetric rolling(ASR), as one of severe plastic deformation(SPD) methods, was widely used to make ultra-fined materials with enhanced performance. Internal marks were used to show the shear deformation during asymmetric rolling with pure aluminium as a model material. Effects of reduction ratio and mismatch ratio on the shear deformation were studied. With the observed shear deformation results, equivalent strain was calculated. For lager shear deformation, rolling equipment was modified to increase friction between specimen and the rollers. Consequently, extremely fine grains with size of 500 nm are obtained in pure aluminium. With improved asymmetric rolling, the ability of grain refinement of ASR is greatly improved.
基金Supported by the Natural Science Foundation of Jiangsu Province(2004BK424)the 135 Key Department Fund of Jiangsu Province(135XY0416)the Outstanding Person Fund of the First Affiliated Hospital of Soochow University(2004YQG05)
文摘MANY cases of pure red cell aplasia(PRCA)were mediated by over-function of immune cells,and responded well to immunosuppressive therapy.1 Sometimes refractory cases also arose.Fludarabine is an analogue of adenosine resistant to deamination which is widely used for B-chronic lymphocytic leukemia(CLL)and other hematological malignancies.2 As a strong immunosuppressive agent,
基金the National Natural Science Foundation of China(69503005)
文摘With the wide acceptance of the computing concept of cluster-based or cluster-of-clusters computing, network-based high performance computing is gaining increasing popularity among parallel computing community. Current parallel environments such as MPI (Message Passing Interface) or BSP (Bulk Synchronous Parallel) can not apply readily to heterogeneous computing platform. In order to exploit the maximum performance potential that a heterogeneous environment brings, we have made some experiments on implementing BSP in pure Java, a fully platform-independent language. The experimental results show that implementation of parallel libraries in Java is feasible and the performance is moderately acceptable. The paper describes our experiences in implementation of BSP in pure Java. Implementation and efficiency issues such as data transport, network communication, support thread, barrier synchronization and dynamic class loading mechanism are discussed in detail.
文摘The Ni3B phase was formed when boron (0.5 at. pct B) was added to the intermetallic of sto- ichiometric and off-stoichiometric (Ni-24 at. pct Al) compounds. In the alloy of stoichiometric composition the particles of Ni3B phase has the size around 0.1μm and is located on the grain boundary of the main phase. The decreasing of concentrations of Al in the ofF-stoichiometric alloy leads to increase in the degree of the long-range order parameter, increasing the concen- trations of boron in the solid solution and decreasing its localization on the grain boundary. Microalloying of boron leads to increasing in the fraction of grain monodomains with disloca- tions up to 0.7 in the alloy of the off-stoichiometric composition and up to 1 in the alloy of the stoichiometric composition. It was established the correlation between the degree of the concentration inhomogeneity, average density of the dislocations and the average long range-order parameter.
文摘A 2-D numerical model was developed to predict the shape of weld pool in stationary GTA welding of commercial pure aluminium,without considering fluid flow in the weld pool.A Gaussian current density and heat input distribution on the surface of the workpiece were considered.The parameters of Gaussian distribution were modified by comparing calculated results with experimental ones.It was found that these distribution parameters are functions of applied current and arc length.Effects of arc length,applied current and welding time on the geometry of the weld pool were investigated.To check the validity of the model,a series of experiments were also conducted.In general,the agreement between calculated overall shape of the weld pool and the experimental one was acceptable,especially in low applied currents.Therefore,it can be concluded that in pure aluminium,the heat conduction is dominant mechanism of heat transfer in the weld pool.
基金supported by Shaan Xi Provincial Natural Science Foundation of China(No.2004E111).
文摘The corrosion resistance of pure magnesium with surface alloying layer obtained by a solid diffusion alloying technique has been analyzed. To establish the optimum treatment time, the experiments were performed at 480℃ for different solid diffusion time (8, 16, and 24h). The diffusion interaction effectiveness between Zn, Al mix powder and the sample surface, depending on the treatment time for diffusion at given temperatures, has an obvious influence on corrosion resistance and corrosion mechanism. Corrosion properties were studied using the constant immersion test (in 3.0% NaCl solution, temperature is (28±1)℃, and time is 96h). Optical microscopy (OM) and EDS (energy dispersive spectrum) composition analysis were used to examine the cross-sectional microstructural characteristics of alloyed layer of treated samples. It is shown that in comparison with the untreated samples, the treated ones possess a better corrosion resistance. The Al5Mg11Zn4 phase, which formed as a continuous phase due to the diffusion of Al, Zn, and Mg elements and subsequent interaction on the outermost layer of diffusion alloying zones (especially the samples treated for 24h at 480℃), was inert to the chloride solution compared with pure magnesium and acted as a corrosion barrier, and therefore the best corrosion resistance was obtained. This protective action of A_(l5)Mg_(11)Zn_4 phase was found to change with its amount, which was controlled by the diffusion time at given temperature. It was concluded that the continuous A_(l5)Mg_(11)Zn_4 phase (WP-zone) of the reacted layer in pure magnesium was beneficial from the point of view of corrosion resistance.
文摘Ultra pure ferritic stainless steel has more advantages in the performance than the ordinary ferritic stainless steel because of ultra low carbon and nitrogen content,such as corrosion resistance,toughness and weldability,etc.Such steel has therefore been applied in many fields,leading to the very rapid development over the past 40 years.This study focuses on the secondary refining process which is the most important step of the whole steelmaking process for the ultra pure ferritic stainless.Firstly,some difficulties of the secondary refining process are described,including the high purification in terms of both carbon and nitrogen contents, high efficient and stable control.Secondly,the development and progress of the secondary refining technology for ultra pure ferritic stainless is introduced in terms of the refining equipments,metallurgical process and assistant technologies.Finally,the prospect was made for the development of secondary refining process for ultra pure ferritic stainless in the future.
文摘A new probability measure for the quantification of entanglement of pure states is introduced.Numerical computations indicate that the derived measure is equal to concurrence,up to the precision of the computer program used.Hence it also provides a physical interpretation for concurrence.