近年来,中央银行数字货币(CBDC)受到全球多个国家和地区的高度关注.双离线交易作为CBDC的可选属性,在无网络连接的情况下进行支付,被认为具有较大的实用价值.面向CBDC的双离线匿名支付场景,基于可信执行环境(TEE)和安全单元(SE)技术,提...近年来,中央银行数字货币(CBDC)受到全球多个国家和地区的高度关注.双离线交易作为CBDC的可选属性,在无网络连接的情况下进行支付,被认为具有较大的实用价值.面向CBDC的双离线匿名支付场景,基于可信执行环境(TEE)和安全单元(SE)技术,提出了一种专为移动平台设计的高效双离线匿名支付方案(dual offline anonymous E-payment for mobile devices,OAPM).OAPM适用于资源受限的移动设备,允许移动付款者在不联网状态下安全地向收款者支付数字货币,且不向收款者及商业银行泄露个人隐私信息,付款者的支付行为也不会被链接,同时允许收款者设备处于离线状态,监管机构(如中央银行)在必要情况下能够识别匿名付款者的真实身份.该方案满足数字货币交易的多项重要属性,包括正确性、不可链接性、可追踪性、不可陷害性、机密性、真实性、防双花性以及可控匿名性等.实现了原型系统,并对可能的参数进行了评估.安全性分析和实验结果表明,该方案从安全性和效率两方面均能满足移动用户CBDC双离线交易的实际需求.展开更多
针对某车型排气尾管低频噪声大问题,利用GT-Power软件建立发动机工作过程与排气消声器耦合仿真分析模型,对排气消声器声学性能和空气动力学性能进行数值计算,分析排气尾管低频噪声大的原因。依据分析结果提出消声器结构优化方案,制作优...针对某车型排气尾管低频噪声大问题,利用GT-Power软件建立发动机工作过程与排气消声器耦合仿真分析模型,对排气消声器声学性能和空气动力学性能进行数值计算,分析排气尾管低频噪声大的原因。依据分析结果提出消声器结构优化方案,制作优化样件进行整车排气尾管噪声试验。试验结果表明,低转速时消声器插入损失提高5d B^7 d B(A),2阶次噪声整体降低,低频噪声问题明显改善。展开更多
应用缺氧/好氧—移动床生物膜反应器(Anoxic/Aerobic-Moving Bed Biofilm Reactor,A/O-MBBR)系统,通过固定进水COD与无机氮之比C/N为12,将COD依次设置为150、300、350和450mg·L^(-1)时,探讨反应器对海水养殖废水中氨氮、硝氮、亚...应用缺氧/好氧—移动床生物膜反应器(Anoxic/Aerobic-Moving Bed Biofilm Reactor,A/O-MBBR)系统,通过固定进水COD与无机氮之比C/N为12,将COD依次设置为150、300、350和450mg·L^(-1)时,探讨反应器对海水养殖废水中氨氮、硝氮、亚硝氮及COD的去除效果,并分析微生物群落变化及响应。结果表明,在进水COD为150mg·L^(-1)、无机氮12.5mg·L^(-1)时,反应器运行效果最佳,此时氨氮、硝氮、COD和亚硝氮的去除率分别为93.7%(出水0.3 mg·L^(-1)),87.5%(出水0.7mg·L^(-1)),98.2%(出水3mg·L^(-1)),86.9%(出水0.1mg·L^(-1))。当COD提高至450mg·L^(-1)时,氨氮去除率逐渐降低到40.7%,亚硝氮在COD为350mg·L^(-1)时去除率降低至22.5%。在整个系统运行过程中,变形菌门(Proteobacteria)和拟杆菌门(Bacteroidetes)是反应器中的绝对优势类群。当COD由150mg·L^(-1)上升到350mg·L^(-1)时,变形菌门的相对丰度却由63.9%~75.2%提高到88.1%~92.4%;拟杆菌门的相对丰度则由11.9%~13.0%降低到4.5%~5.4%;引起污泥膨胀的发硫菌属(Thiothrix)的相对丰度由6.24%~7.08%增加到58.16%~76.74%,表明反应器污泥膨胀趋势加剧。应用A/O-MBBR工艺处理海水养殖废水时,在COD为150mg·L^(-1)时效果较好,随着COD浓度提高,引起污泥膨胀的微生物开始大量滋生。展开更多
We investigate the efficiency at maximum power of a nanothermoelectric heat engine consisting of one spin-degenerate quantum dot embedded between two reservoirs at different temperatures and chemical potentials in an ...We investigate the efficiency at maximum power of a nanothermoelectric heat engine consisting of one spin-degenerate quantum dot embedded between two reservoirs at different temperatures and chemical potentials in an external magnetic field.Based on the stochastic master equation the maximum power and the corresponding efficiency at maximum power are calculated in different external magnetic fields.The result shows that both the maximum power and the corresponding efficiency at maximum power decrease with an increase of the external magnetic field.In the weak magnetic field the corresponding efficiency at maximum power is slightly larger than the Curzon–Ahlborn(CA)efficiency,while in the large magnetic field it is obviously lower than CA efficiency.展开更多
We investigate the thermodynamic performance of a nanosized photoelectric refrigerator consisting of two single energy levels embedded between two reservoirs at different temperatures.Based on the quantum master equat...We investigate the thermodynamic performance of a nanosized photoelectric refrigerator consisting of two single energy levels embedded between two reservoirs at different temperatures.Based on the quantum master equation,expressions for the cooling power and coefficient of performance(COP)of the refrigerator are derived.The characteristic curves between the cooling power and COP are plotted.Moreover,the optimal performance parameters are analyzed by the numerical calculation and graphic method.The influence of the nonradiative processes on the performance characteristics and optimal performance parameters are discussed in detail.展开更多
文摘近年来,中央银行数字货币(CBDC)受到全球多个国家和地区的高度关注.双离线交易作为CBDC的可选属性,在无网络连接的情况下进行支付,被认为具有较大的实用价值.面向CBDC的双离线匿名支付场景,基于可信执行环境(TEE)和安全单元(SE)技术,提出了一种专为移动平台设计的高效双离线匿名支付方案(dual offline anonymous E-payment for mobile devices,OAPM).OAPM适用于资源受限的移动设备,允许移动付款者在不联网状态下安全地向收款者支付数字货币,且不向收款者及商业银行泄露个人隐私信息,付款者的支付行为也不会被链接,同时允许收款者设备处于离线状态,监管机构(如中央银行)在必要情况下能够识别匿名付款者的真实身份.该方案满足数字货币交易的多项重要属性,包括正确性、不可链接性、可追踪性、不可陷害性、机密性、真实性、防双花性以及可控匿名性等.实现了原型系统,并对可能的参数进行了评估.安全性分析和实验结果表明,该方案从安全性和效率两方面均能满足移动用户CBDC双离线交易的实际需求.
文摘针对某车型排气尾管低频噪声大问题,利用GT-Power软件建立发动机工作过程与排气消声器耦合仿真分析模型,对排气消声器声学性能和空气动力学性能进行数值计算,分析排气尾管低频噪声大的原因。依据分析结果提出消声器结构优化方案,制作优化样件进行整车排气尾管噪声试验。试验结果表明,低转速时消声器插入损失提高5d B^7 d B(A),2阶次噪声整体降低,低频噪声问题明显改善。
文摘应用缺氧/好氧—移动床生物膜反应器(Anoxic/Aerobic-Moving Bed Biofilm Reactor,A/O-MBBR)系统,通过固定进水COD与无机氮之比C/N为12,将COD依次设置为150、300、350和450mg·L^(-1)时,探讨反应器对海水养殖废水中氨氮、硝氮、亚硝氮及COD的去除效果,并分析微生物群落变化及响应。结果表明,在进水COD为150mg·L^(-1)、无机氮12.5mg·L^(-1)时,反应器运行效果最佳,此时氨氮、硝氮、COD和亚硝氮的去除率分别为93.7%(出水0.3 mg·L^(-1)),87.5%(出水0.7mg·L^(-1)),98.2%(出水3mg·L^(-1)),86.9%(出水0.1mg·L^(-1))。当COD提高至450mg·L^(-1)时,氨氮去除率逐渐降低到40.7%,亚硝氮在COD为350mg·L^(-1)时去除率降低至22.5%。在整个系统运行过程中,变形菌门(Proteobacteria)和拟杆菌门(Bacteroidetes)是反应器中的绝对优势类群。当COD由150mg·L^(-1)上升到350mg·L^(-1)时,变形菌门的相对丰度却由63.9%~75.2%提高到88.1%~92.4%;拟杆菌门的相对丰度则由11.9%~13.0%降低到4.5%~5.4%;引起污泥膨胀的发硫菌属(Thiothrix)的相对丰度由6.24%~7.08%增加到58.16%~76.74%,表明反应器污泥膨胀趋势加剧。应用A/O-MBBR工艺处理海水养殖废水时,在COD为150mg·L^(-1)时效果较好,随着COD浓度提高,引起污泥膨胀的微生物开始大量滋生。
基金Supported by the National Natural Science Foundation of China under Grant No 11065008.
文摘We investigate the efficiency at maximum power of a nanothermoelectric heat engine consisting of one spin-degenerate quantum dot embedded between two reservoirs at different temperatures and chemical potentials in an external magnetic field.Based on the stochastic master equation the maximum power and the corresponding efficiency at maximum power are calculated in different external magnetic fields.The result shows that both the maximum power and the corresponding efficiency at maximum power decrease with an increase of the external magnetic field.In the weak magnetic field the corresponding efficiency at maximum power is slightly larger than the Curzon–Ahlborn(CA)efficiency,while in the large magnetic field it is obviously lower than CA efficiency.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11065008 and 11365015.
文摘We investigate the thermodynamic performance of a nanosized photoelectric refrigerator consisting of two single energy levels embedded between two reservoirs at different temperatures.Based on the quantum master equation,expressions for the cooling power and coefficient of performance(COP)of the refrigerator are derived.The characteristic curves between the cooling power and COP are plotted.Moreover,the optimal performance parameters are analyzed by the numerical calculation and graphic method.The influence of the nonradiative processes on the performance characteristics and optimal performance parameters are discussed in detail.
