The advantage of recursive programming is that it is very easy to write and it only requires very few lines of code if done correctly.Structured query language(SQL)is a database language and is used to manipulate data...The advantage of recursive programming is that it is very easy to write and it only requires very few lines of code if done correctly.Structured query language(SQL)is a database language and is used to manipulate data.In Microsoft SQL Server 2000,recursive queries are implemented to retrieve data which is presented in a hierarchical format,but this way has its disadvantages.Common table expression(CTE)construction introduced in Microsoft SQL Server 2005 provides the significant advantage of being able to reference itself to create a recursive CTE.Hierarchical data structures,organizational charts and other parent-child table relationship reports can easily benefit from the use of recursive CTEs.The recursive query is illustrated and implemented on some simple hierarchical data.In addition,one business case study is brought forward and the solution using recursive query based on CTE is shown.At the same time,stored procedures are programmed to do the recursion in SQL.Test results show that recursive queries based on CTEs bring us the chance to create much more complex queries while retaining a much simpler syntax.展开更多
Alteration of renal function during SARS-CoV-2 infection is frequent and is associated with excess mortality. It is multifactorial, involving mechanisms more specific to COVID-19: viral invasion, endothelitis and thro...Alteration of renal function during SARS-CoV-2 infection is frequent and is associated with excess mortality. It is multifactorial, involving mechanisms more specific to COVID-19: viral invasion, endothelitis and thrombosis, activation of the renin-angiotensin-aldosterone system, and elevation of pro-inflammatory cytokines. Thus, the objective of this work was to assess renal function in patients with moderate and severe forms of COVID-19. This was a prospective cross-sectional study of patients with COVID-19. The parameters studied were age, sex, uremia, creatinine and glomerular filtration rate (GFR). All biological parameters were measured with the A15 Biosystems automated system (Barcelona, Spain) and the GFR was calculated according to the MDRD formula. Data processing was carried out with the SPSS (Statistical Package for Social Sciences) software version 23. Our study population consisted of 192 subjects with COVID-19, of which 111 were moderate and 81 were severe. The mean age of our subjects was 60 years and a sex ratio of 1.02. GFR assessment showed that 28% of the population had a lowered GFR (<60 mL/min/1.73m<sup>2</sup>). Analysis of the results according to the clinical forms showed frequencies of 19% of disturbance of renal function for the moderate forms against 40% for the severe forms. Impaired renal function appears to be frequent in patients with severe SARS-CoV-2 infection and is associated with a bad prognosis. Any patient hospitalized with SARS-CoV-2 should benefit from an initial nephrological assessment which could be used as a marker to dictate the prognosis of the severity of COVID-19.展开更多
Blends of inorganic nano zirconium dioxide(ZrO-2) and poly(ether-sulfone)(PES) were prepared by mechanical blending. Their mechanical, thermal and electrical properties were investigated. Compared with pure PES, this ...Blends of inorganic nano zirconium dioxide(ZrO-2) and poly(ether-sulfone)(PES) were prepared by mechanical blending. Their mechanical, thermal and electrical properties were investigated. Compared with pure PES, this kind of organic/inorganic nano-composite exhibit a better electrical property, lower coefficients of thermal expansion, as well as a similar thermal properties. The mechanical properties are composition-dependent.展开更多
This work investigates the transient behaviour of a phase change material based cool thermal energy storage (CTES) system comprised of a cylindrical storage tank filled with encapsulated phase change materials (PCMs) ...This work investigates the transient behaviour of a phase change material based cool thermal energy storage (CTES) system comprised of a cylindrical storage tank filled with encapsulated phase change materials (PCMs) in spherical container integrated with an ethylene glycol chiller plant. A simulation program was developed to evaluate the temperature histories of the heat transfer fluid (HTF) and the phase change material at any axial location during the charging period. The results of the model were validated by comparison with experimental results of temperature profiles of HTF and PCM. The model was also used to investigate the effect of porosity, Stanton number, Stefan number and Peclet number on CTES system performance. The results showed that increase in porosity contributes to a higher rate of energy storage. However, for a given geometry and heat transfer coefficient, the mass of PCM charged in the unit decreases as the increase in porosity. The St number as well as the Ste number is also influential in the performance of the unit. The model is a convenient and more suitable method to determine the heat transfer characteristics of CTES system. The results reported are much useful for designing CTES system.展开更多
对毫米波TR(transmitter and receiver)组件焊接过程中线膨胀系数(CTE)失配机理和由于CTE失配导致的热机械应力对组件可靠性的影响进行了分析。根据阶梯焊接温度精确控制和无铅焊料可靠浸润的要求,从实践中总结出了一种真空预镀涂焊接...对毫米波TR(transmitter and receiver)组件焊接过程中线膨胀系数(CTE)失配机理和由于CTE失配导致的热机械应力对组件可靠性的影响进行了分析。根据阶梯焊接温度精确控制和无铅焊料可靠浸润的要求,从实践中总结出了一种真空预镀涂焊接新工艺。实践表明,该新工艺可以精确地进行阶梯焊接温度控制,使无铅焊料有很好的浸润效果,焊透率由70%以下提高到98.3%,延长了CTE不匹配造成的疲劳失效发生时间,提高了TR组件使用可靠性。展开更多
基金financially supported by the Major Special Projects in Anhui Province,China(No.202003c08020005)the Key Projects in Hunan Province,China(No.2020GK2045)+1 种基金the Science and Technology Innovation Program of Hunan Province,China(No.2021RC4036)Postgraduate Scientific Research Innovation Project of Hunan Province,China(No.CX20211079)。
文摘The advantage of recursive programming is that it is very easy to write and it only requires very few lines of code if done correctly.Structured query language(SQL)is a database language and is used to manipulate data.In Microsoft SQL Server 2000,recursive queries are implemented to retrieve data which is presented in a hierarchical format,but this way has its disadvantages.Common table expression(CTE)construction introduced in Microsoft SQL Server 2005 provides the significant advantage of being able to reference itself to create a recursive CTE.Hierarchical data structures,organizational charts and other parent-child table relationship reports can easily benefit from the use of recursive CTEs.The recursive query is illustrated and implemented on some simple hierarchical data.In addition,one business case study is brought forward and the solution using recursive query based on CTE is shown.At the same time,stored procedures are programmed to do the recursion in SQL.Test results show that recursive queries based on CTEs bring us the chance to create much more complex queries while retaining a much simpler syntax.
文摘Alteration of renal function during SARS-CoV-2 infection is frequent and is associated with excess mortality. It is multifactorial, involving mechanisms more specific to COVID-19: viral invasion, endothelitis and thrombosis, activation of the renin-angiotensin-aldosterone system, and elevation of pro-inflammatory cytokines. Thus, the objective of this work was to assess renal function in patients with moderate and severe forms of COVID-19. This was a prospective cross-sectional study of patients with COVID-19. The parameters studied were age, sex, uremia, creatinine and glomerular filtration rate (GFR). All biological parameters were measured with the A15 Biosystems automated system (Barcelona, Spain) and the GFR was calculated according to the MDRD formula. Data processing was carried out with the SPSS (Statistical Package for Social Sciences) software version 23. Our study population consisted of 192 subjects with COVID-19, of which 111 were moderate and 81 were severe. The mean age of our subjects was 60 years and a sex ratio of 1.02. GFR assessment showed that 28% of the population had a lowered GFR (<60 mL/min/1.73m<sup>2</sup>). Analysis of the results according to the clinical forms showed frequencies of 19% of disturbance of renal function for the moderate forms against 40% for the severe forms. Impaired renal function appears to be frequent in patients with severe SARS-CoV-2 infection and is associated with a bad prognosis. Any patient hospitalized with SARS-CoV-2 should benefit from an initial nephrological assessment which could be used as a marker to dictate the prognosis of the severity of COVID-19.
文摘Blends of inorganic nano zirconium dioxide(ZrO-2) and poly(ether-sulfone)(PES) were prepared by mechanical blending. Their mechanical, thermal and electrical properties were investigated. Compared with pure PES, this kind of organic/inorganic nano-composite exhibit a better electrical property, lower coefficients of thermal expansion, as well as a similar thermal properties. The mechanical properties are composition-dependent.
文摘This work investigates the transient behaviour of a phase change material based cool thermal energy storage (CTES) system comprised of a cylindrical storage tank filled with encapsulated phase change materials (PCMs) in spherical container integrated with an ethylene glycol chiller plant. A simulation program was developed to evaluate the temperature histories of the heat transfer fluid (HTF) and the phase change material at any axial location during the charging period. The results of the model were validated by comparison with experimental results of temperature profiles of HTF and PCM. The model was also used to investigate the effect of porosity, Stanton number, Stefan number and Peclet number on CTES system performance. The results showed that increase in porosity contributes to a higher rate of energy storage. However, for a given geometry and heat transfer coefficient, the mass of PCM charged in the unit decreases as the increase in porosity. The St number as well as the Ste number is also influential in the performance of the unit. The model is a convenient and more suitable method to determine the heat transfer characteristics of CTES system. The results reported are much useful for designing CTES system.
文摘对毫米波TR(transmitter and receiver)组件焊接过程中线膨胀系数(CTE)失配机理和由于CTE失配导致的热机械应力对组件可靠性的影响进行了分析。根据阶梯焊接温度精确控制和无铅焊料可靠浸润的要求,从实践中总结出了一种真空预镀涂焊接新工艺。实践表明,该新工艺可以精确地进行阶梯焊接温度控制,使无铅焊料有很好的浸润效果,焊透率由70%以下提高到98.3%,延长了CTE不匹配造成的疲劳失效发生时间,提高了TR组件使用可靠性。
