The densification and the fractal dimensions of carbon-nickel films annealed at different temperatures 300, 500, 800, and 1000℃ with emphasis on porosity evaluation are investigated. For this purpose, the refractive...The densification and the fractal dimensions of carbon-nickel films annealed at different temperatures 300, 500, 800, and 1000℃ with emphasis on porosity evaluation are investigated. For this purpose, the refractive index of films is determined from transmittance spectra. Three different regimes are identified, T 〈 500℃, 500℃ 〈 T 〈 800℃ and T 〉 800℃. The Rutherford baekscattering spectra show that with increasing the annealing temperature, the concentration of nickel atoms into films decreases. It is shown that the effect of annealing temperatures for increasing films densification at T 〈 500℃ and T 〉 800℃ is greater than the effect of nickel concentrations. It is observed that the effect of decreasing nickel atoms into films at 500℃ 〈 T 〈 800℃ strongly causes improving porosity and decreasing densification. The fractal dimensions of carbon-nickel films annealed from 300 to 500℃ are increased, while from 500 to 1000℃ these characteristics are decreased. It can be seen that at 800℃, films have maximum values of porosity and roughness.展开更多
This paper presents a new idea for an a lyzing the complicated shock signal.Based on this kind of analysis,an equivale nt power spectral density(PSD) chart is drawn for vibration environmental test,which is carried to...This paper presents a new idea for an a lyzing the complicated shock signal.Based on this kind of analysis,an equivale nt power spectral density(PSD) chart is drawn for vibration environmental test,which is carried to test the vehicle loading instrument's vibration behavior.T he environment test is equivalent to the condition under which the vehicle and t he instrument is experiencing a firing period.Exactly speaking,the short time vibration during the firing period is a complicated shock event.The paper point s out the deficiency of the commonly used half sine equivalence for the shock an d vibration environment test and gives the procedure of how to draw the PSD char t through the actual acceleration data.展开更多
随机振动台根据功率谱密度(PSD,Power Spectral Density)生成的信号为高斯信号,而实际振动环境有时是非高斯的,因此随机振动实验常常无法准确模拟产品在真实振动环境下的失效情况.通过两个案例分别对均方根值(RMS,Root Mean Square)不...随机振动台根据功率谱密度(PSD,Power Spectral Density)生成的信号为高斯信号,而实际振动环境有时是非高斯的,因此随机振动实验常常无法准确模拟产品在真实振动环境下的失效情况.通过两个案例分别对均方根值(RMS,Root Mean Square)不随时间变化和随时间变化的非高斯随机振动进行了模拟方法研究.案例1利用Hermite多项式法对高斯信号进行了转换,在保证功率谱密度不变的同时得到了具有指定峭度的RMS不随时间变化的非高斯信号,但该方法对于输入的峭度有限制,当输入峭度大于10时,误差达到了20%.案例2利用一种新方法对实测的RMS随时间变化的非高斯振动进行了模拟,模拟后得到的非高斯信号和实测信号具有相同的功率谱密度、峭度以及概率分布,验证了新方法的准确性.展开更多
文摘The densification and the fractal dimensions of carbon-nickel films annealed at different temperatures 300, 500, 800, and 1000℃ with emphasis on porosity evaluation are investigated. For this purpose, the refractive index of films is determined from transmittance spectra. Three different regimes are identified, T 〈 500℃, 500℃ 〈 T 〈 800℃ and T 〉 800℃. The Rutherford baekscattering spectra show that with increasing the annealing temperature, the concentration of nickel atoms into films decreases. It is shown that the effect of annealing temperatures for increasing films densification at T 〈 500℃ and T 〉 800℃ is greater than the effect of nickel concentrations. It is observed that the effect of decreasing nickel atoms into films at 500℃ 〈 T 〈 800℃ strongly causes improving porosity and decreasing densification. The fractal dimensions of carbon-nickel films annealed from 300 to 500℃ are increased, while from 500 to 1000℃ these characteristics are decreased. It can be seen that at 800℃, films have maximum values of porosity and roughness.
文摘This paper presents a new idea for an a lyzing the complicated shock signal.Based on this kind of analysis,an equivale nt power spectral density(PSD) chart is drawn for vibration environmental test,which is carried to test the vehicle loading instrument's vibration behavior.T he environment test is equivalent to the condition under which the vehicle and t he instrument is experiencing a firing period.Exactly speaking,the short time vibration during the firing period is a complicated shock event.The paper point s out the deficiency of the commonly used half sine equivalence for the shock an d vibration environment test and gives the procedure of how to draw the PSD char t through the actual acceleration data.
文摘随机振动台根据功率谱密度(PSD,Power Spectral Density)生成的信号为高斯信号,而实际振动环境有时是非高斯的,因此随机振动实验常常无法准确模拟产品在真实振动环境下的失效情况.通过两个案例分别对均方根值(RMS,Root Mean Square)不随时间变化和随时间变化的非高斯随机振动进行了模拟方法研究.案例1利用Hermite多项式法对高斯信号进行了转换,在保证功率谱密度不变的同时得到了具有指定峭度的RMS不随时间变化的非高斯信号,但该方法对于输入的峭度有限制,当输入峭度大于10时,误差达到了20%.案例2利用一种新方法对实测的RMS随时间变化的非高斯振动进行了模拟,模拟后得到的非高斯信号和实测信号具有相同的功率谱密度、峭度以及概率分布,验证了新方法的准确性.
