The microstructure and composition of TiC-A12O3/Fe functionally graded materials (FGM) prepared by self-propagating high temperature synthesis and pseudo-hot isostatic pressing (SHS/ PHIP) were studied, and the resist...The microstructure and composition of TiC-A12O3/Fe functionally graded materials (FGM) prepared by self-propagating high temperature synthesis and pseudo-hot isostatic pressing (SHS/ PHIP) were studied, and the resisting thermal shock behaviors were analyzed. The results show that TiC-A12O3/Fe FGM has graded composition distribution. No cross-section crack through the layers was found in the tests of thermal shock and fatigue.展开更多
A novel fluorescent sensor was prepared from sulfonated calix[4]arene(SC4A)by the host-guest com-plexation method using the fluorescent dye rhodamine B(RB)as a structure-directing agent.The crystal structure of the ho...A novel fluorescent sensor was prepared from sulfonated calix[4]arene(SC4A)by the host-guest com-plexation method using the fluorescent dye rhodamine B(RB)as a structure-directing agent.The crystal structure of the host-guest complex(RB@(SC4A)_(3))was confirmed by X-ray diffraction studies while its performance and sensing mechanism for metal ion pollutants were characterized using fluorescence and nuclear magnetic resonance spectroscopies.The results showed that RB@(SC4A)_(3) had a triangular branch structure resulting from host-guest mediation of the interactions between the three SC4A host molecules and the three terminal groups of the guest molecule RB.The host-guest complex exhibited sensitive and selective sensing towards Fe^(3+)ions via a fluorescence quenching mechanism.The results indicated that RB@(SC4A)_(3) could be a promising sensitive and selective fluorescent sensor for metal ion pollutants mon-itoring.It also provided new insights into the synthesis of calixarene-based host-guest complex.展开更多
In this paper, a novel pulse interference filter for fiber Bragg grating （FBG） interrogation based on the tunable Fabry-Perot （F-P） filtering principle is proposed and experimentally demonstrated. The self-develop...In this paper, a novel pulse interference filter for fiber Bragg grating （FBG） interrogation based on the tunable Fabry-Perot （F-P） filtering principle is proposed and experimentally demonstrated. The self-developed FBG interrogation system is devised for the aircraft health management of key structures. Nevertheless, the pulse interference is detected in the reflection spectrum of FBG causing interrogation system unstable. To address the problem, the first-order lag pulse broadening filter is proposed in this paper. The first-order lag filter is applied to preprocess and smooth the original signal, meanwhile enhancing the signal-to-noise ratio （SNR）. Afterwards, peaks of reflection spectrum are distinguished with pulse interference by pulse broadening. Experimental results indicate that 634 peaks are detected before adopting the first-order lag pulse broadening filter. Comparatively, the number of peaks decreases to 203 after filtering the interference pulse, and the correct rate of peak detection is higher than 98.5%. Through the comparison with the finite impulse response （FIR） filter, the advantage of first-order lag filter is proved. The vibration monitoring experiment demonstrates that this system has high dynamic precision with a dynamic interrogation range of 0Hz-400Hz, and the maximum repetition rate of 800Hz.展开更多
In recent years,many studies have been conducted in the field of firearm identification with the objective of providing an objective method of evaluating the comparison of cartridge cases.However,less attention has be...In recent years,many studies have been conducted in the field of firearm identification with the objective of providing an objective method of evaluating the comparison of cartridge cases.However,less attention has been paid to the objective evaluation of bullet comparisons.In this study,1000 registered Chinese Norinco QSZ-92 pistols were used,and a database of 2996 bullets was constructed.Both the receiver operating characteristic(ROC)curve and the score-based likelihood ratio method were used to objectively evaluate the similarity scores derived by the EvofinderVR system.The results indicate that this system has excellent ability to discriminate between the selected pistols.This paper proposes an objective evaluation method,which serves as a response to the ongoing debates regarding the foundation of the discipline.展开更多
The specificity of marks was evaluated by differences between marks left by the same firearm(within variability)and differences between marks left by different firearms(between variability).The within variability and ...The specificity of marks was evaluated by differences between marks left by the same firearm(within variability)and differences between marks left by different firearms(between variability).The within variability and between variability of firing pin impressions and breech face marks on cartridge cases from over 3070 consecutive firings of a Chinese Norinco QSZ‑929 mm pistol were investigated based on the automated ballistic identification system Evofinder®.The first 20 cartridge cases and one random specimen out of every set of 10 consecutive cartridge cases of the remaining 3050 cases were entered into the Evofinder®system.Thus,325 cartridges fired from the same pistol were used to estimate the within variability.Then,88 cartridges fired from 88 different pistols of the same model(one cartridge each)were used to estimate the between variability.This study established a database containing 413 cartridges.We used the 325 cartridges fired from the same pistol as a correlation baseline in the database.Both firing pin and breech scores and gaps between these scores were used to analyze the variability.In the score evaluation process,a likelihood ratio system was used to evaluate the likelihood ratio performance.The Evofinder®system correctly discriminated the matches,and the likelihood ratios provided strong support for the true state of the hypothesis.In addition,we found that the score gap was usually greater than the other score differences by more than 1000%in firing pin list and 100%in the breech list.Further analysis of the score and gap can help examiners use the Evofinder®system more efficiently.展开更多
文摘The microstructure and composition of TiC-A12O3/Fe functionally graded materials (FGM) prepared by self-propagating high temperature synthesis and pseudo-hot isostatic pressing (SHS/ PHIP) were studied, and the resisting thermal shock behaviors were analyzed. The results show that TiC-A12O3/Fe FGM has graded composition distribution. No cross-section crack through the layers was found in the tests of thermal shock and fatigue.
基金the National Natural Science Foundation of China (NSFC, No. 21861011)the Innovation Program for High-level Talents of Guizhou Province (No. 2016–5657) are gratefully acknowledged for financial support
文摘A novel fluorescent sensor was prepared from sulfonated calix[4]arene(SC4A)by the host-guest com-plexation method using the fluorescent dye rhodamine B(RB)as a structure-directing agent.The crystal structure of the host-guest complex(RB@(SC4A)_(3))was confirmed by X-ray diffraction studies while its performance and sensing mechanism for metal ion pollutants were characterized using fluorescence and nuclear magnetic resonance spectroscopies.The results showed that RB@(SC4A)_(3) had a triangular branch structure resulting from host-guest mediation of the interactions between the three SC4A host molecules and the three terminal groups of the guest molecule RB.The host-guest complex exhibited sensitive and selective sensing towards Fe^(3+)ions via a fluorescence quenching mechanism.The results indicated that RB@(SC4A)_(3) could be a promising sensitive and selective fluorescent sensor for metal ion pollutants mon-itoring.It also provided new insights into the synthesis of calixarene-based host-guest complex.
文摘In this paper, a novel pulse interference filter for fiber Bragg grating （FBG） interrogation based on the tunable Fabry-Perot （F-P） filtering principle is proposed and experimentally demonstrated. The self-developed FBG interrogation system is devised for the aircraft health management of key structures. Nevertheless, the pulse interference is detected in the reflection spectrum of FBG causing interrogation system unstable. To address the problem, the first-order lag pulse broadening filter is proposed in this paper. The first-order lag filter is applied to preprocess and smooth the original signal, meanwhile enhancing the signal-to-noise ratio （SNR）. Afterwards, peaks of reflection spectrum are distinguished with pulse interference by pulse broadening. Experimental results indicate that 634 peaks are detected before adopting the first-order lag pulse broadening filter. Comparatively, the number of peaks decreases to 203 after filtering the interference pulse, and the correct rate of peak detection is higher than 98.5%. Through the comparison with the finite impulse response （FIR） filter, the advantage of first-order lag filter is proved. The vibration monitoring experiment demonstrates that this system has high dynamic precision with a dynamic interrogation range of 0Hz-400Hz, and the maximum repetition rate of 800Hz.
基金This study received funding from the Opening Project of Shanghai Key Laboratory of Crime Scene Evidence[grant number 2018XCWZK18].
文摘In recent years,many studies have been conducted in the field of firearm identification with the objective of providing an objective method of evaluating the comparison of cartridge cases.However,less attention has been paid to the objective evaluation of bullet comparisons.In this study,1000 registered Chinese Norinco QSZ-92 pistols were used,and a database of 2996 bullets was constructed.Both the receiver operating characteristic(ROC)curve and the score-based likelihood ratio method were used to objectively evaluate the similarity scores derived by the EvofinderVR system.The results indicate that this system has excellent ability to discriminate between the selected pistols.This paper proposes an objective evaluation method,which serves as a response to the ongoing debates regarding the foundation of the discipline.
基金This work has received funding from the Opening Project of Shanghai Key Laboratory of Crime Scene Evidence(2018XCWZK18).
文摘The specificity of marks was evaluated by differences between marks left by the same firearm(within variability)and differences between marks left by different firearms(between variability).The within variability and between variability of firing pin impressions and breech face marks on cartridge cases from over 3070 consecutive firings of a Chinese Norinco QSZ‑929 mm pistol were investigated based on the automated ballistic identification system Evofinder®.The first 20 cartridge cases and one random specimen out of every set of 10 consecutive cartridge cases of the remaining 3050 cases were entered into the Evofinder®system.Thus,325 cartridges fired from the same pistol were used to estimate the within variability.Then,88 cartridges fired from 88 different pistols of the same model(one cartridge each)were used to estimate the between variability.This study established a database containing 413 cartridges.We used the 325 cartridges fired from the same pistol as a correlation baseline in the database.Both firing pin and breech scores and gaps between these scores were used to analyze the variability.In the score evaluation process,a likelihood ratio system was used to evaluate the likelihood ratio performance.The Evofinder®system correctly discriminated the matches,and the likelihood ratios provided strong support for the true state of the hypothesis.In addition,we found that the score gap was usually greater than the other score differences by more than 1000%in firing pin list and 100%in the breech list.Further analysis of the score and gap can help examiners use the Evofinder®system more efficiently.
