The mechanical balance process is the key process to eliminate the quadrature error and improve the performance of the cupped wave gyro. The conventional mechanical balance method for cupped wave gyro based on cup-wal...The mechanical balance process is the key process to eliminate the quadrature error and improve the performance of the cupped wave gyro. The conventional mechanical balance method for cupped wave gyro based on cup-wall trimming requires high control accuracy of trimming quantity, which increases the production cost and decreases the fabrication efficiency in large extent. However, it is hard to reach the high balance accuracy with the natural frequency split of mHz grade by using the conventional method. In this paper, the lumped mass dynamic model of the cupped wave gyro is built by discretization method, and the effects of different position trimming on the natural frequency are analyzed. It is pointed out that trimming off a tiny quantity of material from cup-wall causes large variation of the natural frequency is the main reason for the low accuracy of the conventional mechanical balance method. Then, a precision balance method for cupped wave gyro based on cup-bottom trimming is presented and the entire procedures of this method are given. The static balance process and dynamic balance process of the precision balance method are simulated by the finite element software. The simulation result shows that the precision balance method based on cup-bottom trimming brings less additional natural frequency split in the static balance process, minimizes the natural frequency split to mHz grade and rectify the angle of mode offset to 0.1° grade in the dynamic balance process, furthermore, the method decreases the requirement for control accuracy of trimming quantity evidently. The research work provides references for structure optimization design and balance process plan of the cupped wave gyro.展开更多
Airborne pulse Doppler radar is a key threat to the military helicopter,and assessing the stealth performance of helicopter against airborne early warning radar is helpful to the helicopter’s stealth design and opera...Airborne pulse Doppler radar is a key threat to the military helicopter,and assessing the stealth performance of helicopter against airborne early warning radar is helpful to the helicopter’s stealth design and operational planning.In this paper,the Shooting and Bouncing Ray(SBR)and Uniform Theory of Diffraction(UTD)based high-frequency algorithms are used to calculate the Radar Cross Section(RCS)of helicopter,and the radar range equations are used to evaluate the stealth performance.In order to account for the effects of rotor flapping motions during actual flight,the aerodynamics model of whole helicopter is established and the attitudes and controls of helicopter at different flight states are trimmed and input into the RCS calculation module.The effects of helicopter flight speed,flying direction and operational environment on radar stealth performance are studied in focus.It is demonstrated by the results that the trimming control does have a great influence of more than 5 dB on the RCS of helicopter,and the introduction of the trim calculation brings the helicopter’s returns calculation closer to the reality.Variations in flight speed lead to the changes in the stealth performance of helicopter against Early Warning Aircraft(EWA),and the helicopter flight speed can be planned according to the operational requirements to minimize exposure distance or exposure time.Variations in flying direction mainly affect the detection properties of helicopter returns,and flying in the same direction with EWA usually gives the helicopter better low-observability than flying head-on.Variations in operational environment mainly affect the radar detection performance and the sensitivity of the detection performance to external factors;the same amount of change in some external factor causes a different amount of change in the helicopter’s detectability in different environments.展开更多
In this paper, we introduce a z-axis quartz gyroscope using a double-H tuning fork, which has a high sensitivity. However, it also causes a large mechanical quadrature error. The laser trimming method is used to suppr...In this paper, we introduce a z-axis quartz gyroscope using a double-H tuning fork, which has a high sensitivity. However, it also causes a large mechanical quadrature error. The laser trimming method is used to suppress this error at quartz level. The trimming law is obtained through the finite element method （FEM）. A femtosecond laser processing system is used to trim the gold balancing masses on the beams, and experimental results are basically consistent with the simulated ones. The mechanical quadrature error is suppressed by 96%, from 26.3° s-1 to 1.1° s-1. Nonlinearity changes from 1.48% to 0.30%, angular random walk （ARW） is reduced from 2.19° h-1/2 to 1.42° h-1/2, and bias instability is improved by a factor of 7.7, from 197.6° h-1 to 25.4° h-1.展开更多
Based on the elastic-plastic large deformation finite element formulation as well as the shell element combined discrete Kirchhoff theoretical plate element (DKT) with membrane square element, deep-drawing bending spr...Based on the elastic-plastic large deformation finite element formulation as well as the shell element combined discrete Kirchhoff theoretical plate element (DKT) with membrane square element, deep-drawing bending springback of typical U-pattern is studied. At the same time the springback values of the drawing of patterns' unloading and trimming about the satellite aerial reflecting surface are predicted and also compared with those of the practical punch. Above two springbacks all obtain satisfactory results, which provide a kind of effective quantitative pre-prediction of springback for the practical engineers.展开更多
AIM:To evaluate the efficacy and safety of endoscopic removal and trimming of self-expandable metallic stents(SEMS).METHODS:All SEMS had been placed for distal biliary strictures.Twenty-seven endoscopic procedures wer...AIM:To evaluate the efficacy and safety of endoscopic removal and trimming of self-expandable metallic stents(SEMS).METHODS:All SEMS had been placed for distal biliary strictures.Twenty-seven endoscopic procedures were performed in 19 patients in whom SEMS(one uncovered and 18 covered) removal had been attempted,and 8 patients in whom stent trimming using argon plasma coagulation(APC) had been attempted at Tokyo Medical University Hospital.The APC settings were:voltage 60-80 W and gas flow at 1.5 L/min.RESULTS:The mean stent indwelling period for all patients in whom stent removal had been attempted was 113.7 ± 77.6 d(range,8-280 d).Of the 19 patients in whom removal of the SEMS had been attempted,the procedure was successful in 14(73.7%) without procedure-related adverse events.The indwelling period in the stent removable group was shorter than that in the unremovable group(94.9 ± 71.5 d vs 166.2 ± 76.2 d,P = 0.08).Stent trimming was successful for all patients with one minor adverse event consisting of self-limited hemorrhage.Trimming time ranged from 11 to 16 min.CONCLUSION:Although further investigations on larger numbers of cases are necessary to accumulate evidence,the present data suggested that stent removal and stent trimming is feasible and effective for stent-related complications.展开更多
Beak trimming was a part of routine husbandry for poultry industry,which was the most efficient and economic way to reduce the incidence of cannibalism.However,the controversy about young chicken trimming still exits ...Beak trimming was a part of routine husbandry for poultry industry,which was the most efficient and economic way to reduce the incidence of cannibalism.However,the controversy about young chicken trimming still exits and it was drawing more concern recently along with the popular of animal behavior and welfare theory.To evaluate the influence of beak trimming on young chicken spleen development and find the key regulators of the spleen development,in this study,the electron microscope technique,flow cytometry and immunohistochemical techniques were used to investigate the effects of beak trimming stress on the spleen development.The result of electronic microscope showed that significant stress response could be found in chicken spleen cells after beak trimming.Cell volume became larger,chromatin of cell nuclear agglutinated conglobation,cytoplasm formed more vacuole,and mitochondria emerged vacuolization phenomenon in splenic lymphocyte after beak trimming.From the flow cytometry,the lymphocyte of spleen in the control group and experimental group were mainly in G1 phase,and the remaining small amount was in S and M phases.Of interest,the number of the lymphocyte which are in G1 phase within immune organ in the experimental group were more than that in the control group,but the number of cells in S and M phases were less than that in the control group.And beak trimming decreased the lymphocytes proliferation index of spleen.Inmmuohistochemical result showed that the beak trimming stress did not affect the expression sites of two apoptosis-related genes,Bcl-2 and Bax,in the spleen.But the expression level of Bcl-2 decreased while Bax increased in chicken immune organs after beak trimming.Furthermore,the beak trimming increased spleen cell apoptosis with a time-dependant style.Our findings may make a contribution to the active precaution of stress response.展开更多
Mangrove forests in southern Iran are of high ecological and economic importance.These forests are being threatened because of uncontrolled harvesting to provide fodder for livestock.The objective of this study is to ...Mangrove forests in southern Iran are of high ecological and economic importance.These forests are being threatened because of uncontrolled harvesting to provide fodder for livestock.The objective of this study is to provide recommendations for appropriate harvesting intensities by quantifying the effect of different harvesting intensities on vegetative and vigor characteristics of mangrove trees.This study was conducted using a randomized complete block design comprising four treatments(10.00%,20.00%,and 30.00% trimming,along with a control)replicated three times.Vegetative characteristics were measured before and after trimming(five-year period)and analyzed using generalized linear model statistical analysis.The growths of the average diameter of canopy,canopy area,canopy volume,canopy height,tree height,and collar diameter in the control treatment were all significantly higher than those in the trimming treatments.In addition,there was a decreasing trend in leaf fresh and dry mass,leaf area index,total area of canopy leaves,and health status of tree in the trimming treatments.For example,the percentage change in fresh and dry leaf mass in the control treatment was positive(29.87% and 38.31%,respectively),whereas the trimming treatments of 10.00%,20.00% and 30.00% had negative effects(-7.01% and -4.79%,-11.32% and -14.30%,and -15.84% and -17.29%,respectively).In addition,the changes in leaf area index in the control(4.95%)and 30.00% trimming(-24.57%)treatments were the highest and lowest,respectively.The percentage change in soil organic matter in the control,10.00%,20.00%,and 30.00% treatments were 22.94%,-9.90%,-16.91%,and -18.68%,respectively.The study demonstrated that gray mangrove trees were highly sensitive to canopy trimming,with even minimal trimming intensities negatively affecting vegetative growth and soil organic matter.Therefore,it is recommended that cutting and trimming of mangrove trees should be prevented even at low intensity to preserve mangrove ecosystem health and resilience against environmental stressors.展开更多
In order to effectively remove the residual Ge atoms at the surface of channel and improve the interfacial characteristic of gate-all-around(GAA)Si nanosheet field effect transistors,a low-temperature atomic-level tri...In order to effectively remove the residual Ge atoms at the surface of channel and improve the interfacial characteristic of gate-all-around(GAA)Si nanosheet field effect transistors,a low-temperature atomic-level trimming approach using ammonia peroxide water mixture(APM)solution treatment followed by diluted hydrofluoric acid is proposed and carried out.The capacitor samples with SiGe epitaxy layer,similar thermal budget and channel release process were fabricated using advanced high-k/metal-gate.An 83%reduction in surface roughness at atomic level is obtained by increasing APM treatment time.Moreover,there are 99.45% reduction in the interface state density(D_(it))and 96.8%leakage reduction in current density(J_(g))after APM treatment,indicating a promising method for future GAA NSFET performance optimization.展开更多
The frequency mismatch caused by material defects and geometric errors during the manufacturing process is a critical factor limiting the performance of micro-shell resonator gyroscope(MSRG).Compared with other MEMS g...The frequency mismatch caused by material defects and geometric errors during the manufacturing process is a critical factor limiting the performance of micro-shell resonator gyroscope(MSRG).Compared with other MEMS gyroscopes,the frequency mismatch of MSRG can fundamentally be reduced by mechanical trimming.However,it is challenged by the precise characterization.Previous studies about the characterization of frequency mismatch are almost based on frequency spectrum analysis and sweeping,which can only meet the requirement of trimming efficiency of over 100 mHz,limited by the signal noise and temperature drift.In this paper,a novel characterization method of frequency mismatch based on the quadrature-control force under the self-precession mode is proposed to meet the requirement of high-precision mechanical trimming.Furthermore,the phase errors which affect the accuracy of characterization is analyzed,and methods for the correction of phase errors are proposed.Based on this characterization method,0.32 mHz frequency mismatch of micro-shell resonator is achieved by mechanical trimming,which is the best-reported performance for mechanical trimming of MEMS gyroscopes so far.More importantly,this novel characterization method can be applied for other kinds of resonators which can be mechanical trimmed.展开更多
This study proposes a novel tool wear model for the edge trimming process of carbon fiber-reinforced plasticities(CFRPs).The main innovation is that the model considers the actual wear state of both the planar flank f...This study proposes a novel tool wear model for the edge trimming process of carbon fiber-reinforced plasticities(CFRPs).The main innovation is that the model considers the actual wear state of both the planar flank face and the semicylindrical cutting edge.In addition,for the whole wear process,the model illustrates the dynamic wear condition by introducing a varying wear coefficient determined by the instantaneous force‒temperature condition and relative movement distance.The analytical results of the tool wear law suggest that cutting edge wear depends on tool nose rigidity and the practical contact distance with the CFRP workpiece mainly.To suppress cutting edge wear,reducing the rake angle and flank angle to improve rigidity and selecting a low spindle speed and high feed rate to decrease the practical cutting distance are recommended.The wear of the flank face is mainly determined by the flank angle and bouncing back height of the machined surface.To reduce its wear,a large flank angle,high spindle speed,and low feed rate are recommended.Since the strategies for reducing the wear of the cutting edge and flank faces are contradictory,to reduce tool wear more effectively,reducing cutting-edge wear is prioritized.展开更多
This study presents a scheme for the identification and trimming of the first three harmonics of mass defects in micro hemispherical resonators(MHRs),aiming to refine their mass balancing techniques.Given the manufact...This study presents a scheme for the identification and trimming of the first three harmonics of mass defects in micro hemispherical resonators(MHRs),aiming to refine their mass balancing techniques.Given the manufacturing and structural uniqueness of MHRs,a multimodal elastic electrode substrate is designed to respond to the first three harmonics.Configured as cantilever beams with a load platform,this substrate forms an identification assembly with the MHR.The radial eccentric forces generated by the 1st and 3rd harmonics in the MHR can excite the swing modes of the assembly,while the axial force generated by the 2nd harmonic can induce axial mode vibrations along the Z-axis.A method is proposed to decompose the vibration information of the elastic electrode substrate into doublecycle,single-cycle,and offset components under the N=2 modes,enabling the extraction of swing mode and Z-axis translational mode response signals and the retro-calculation of the first three harmonics.Finite element simulation,based on a model of the identification assembly,validates the proposed scheme by simulating the identification and trimming process.Subsequently,an identification assembly sample is fabricated and subjected to identification and trimming of the first three harmonics using a laser vibrometer and femtosecond laser ablation process.After multiple iterations,the first three harmonics are reduced by 92.8%,89.3%,and 75.5%,respectively,effectively suppressing the swing modes and axial translation modes induced by unbalanced mass.展开更多
A low temperature drift curvature-compensated complementary metal oxide semiconductor (CMOS) bandgap ref-erence is proposed.A dual-differential-pair amplifier was employed to add compensation with a high-order term of...A low temperature drift curvature-compensated complementary metal oxide semiconductor (CMOS) bandgap ref-erence is proposed.A dual-differential-pair amplifier was employed to add compensation with a high-order term of TlnT (T is the thermodynamic temperature) to the traditional 1st-order compensated bandgap.To reduce the offset of the amplifier and noise of the bandgap reference,input differential metal oxide semiconductor field-effect transistors (MOSFETs) of large size were used in the amplifier and to keep a low quiescent current,these MOSFETs all work in weak inversion.The voltage reference's temperature curvature has been further corrected by trimming a switched resistor network.The circuit delivers an output voltage of 3 V with a low dropout regulator (LDO).The chip was fabricated in Taiwan Semiconductor Manufacturing Company (TSMC)'s 0.35-μm CMOS process,and the temperature coefficient (TC) was measured to be only 2.1×10 6/°C over the temperature range of 40-125 °C after trimming.The power supply rejection (PSR) was 100 dB @ DC and the noise was 42 μV (rms) from 0.1 to 10 Hz.展开更多
In this research,the effects of heat treatment together with xylose and cysteine addition on the amino acid changes and volatile compound generation in non-enzymatic pork trimmings extract(NPE)or enzymatic pork trimmi...In this research,the effects of heat treatment together with xylose and cysteine addition on the amino acid changes and volatile compound generation in non-enzymatic pork trimmings extract(NPE)or enzymatic pork trimmings hydrolysate(EPH)were studied.Enzymatic hydrolysis significantly increased the total amino acid content and provided necessary precursors for the thermal reactions.The addition of xylose assisted the browning process while the cysteine addition partially inhibited the formation of brown colour in both NPE and EPH.The addition of both cysteine and xylose significantly increased the formation of sulfur-containing volatile flavour compounds in EPH samples,but not in NPE samples.The characteristic“roasted meat”like aromatic volatile compounds,in particular,2-furfurylthiol,were only detected in EPH samples at 8.13 ng/mL,when both xylose(35 mg/mL)and cysteine(10 mg/mL)were added.展开更多
We demonstrate a novel high-accuracy post-fabrication trimming technique to fine-tune the phase of integrated Mach–Zehnder interferometers, enabling permanent correction of typical fabrication-based phase errors. The...We demonstrate a novel high-accuracy post-fabrication trimming technique to fine-tune the phase of integrated Mach–Zehnder interferometers, enabling permanent correction of typical fabrication-based phase errors. The effective index change of the optical mode is 0.19 in our measurement, which is approximately an order of magnitude improvement compared to previous work with similar excess optical loss. Our measurement results suggest that a phase accuracy of 0.078 rad was achievable with active feedback control.展开更多
Ceramic structural parts are one of the most widely utilized structural parts in the industry. However, they usually contain defects following the pressing process, such as burrs. Therefore, additional trimming is usu...Ceramic structural parts are one of the most widely utilized structural parts in the industry. However, they usually contain defects following the pressing process, such as burrs. Therefore, additional trimming is usually required, despite the deformation challenges and difficulty in positioning. This paper proposes an ultrafast laser processing system for trimming complex ceramic structural parts. Opto-electromechanical cooperative control software is developed to control the laser processing system. The trimming problem of the ceramic cores used in aero engines is studied. The regional registration method is introduced based on the iterative closest point algorithm to register the path extracted from the computer-aided design model with the deformed ceramic core. A zonal and layering processing method for three-dimensional contours on complex surfaces is proposed to generate the working data of high-speed scanning galvanometer and the computer numerical control machine tool, respectively. The results show that the laser system and the method proposed in this paper are suitable for trimming complex non-datum parts such as ceramic cores. Compared with the results of manual trimming, the method proposed in this paper has higher accuracy, efficiency, and yield. The method mentioned above has been used in practical application with satisfactory results.展开更多
This work presented a trimming technique and algorithm applied in a capacitive successive approximation register（SAR） analog to digital converter（ADC） for a sensor interface, which can be integrated with the prece...This work presented a trimming technique and algorithm applied in a capacitive successive approximation register（SAR） analog to digital converter（ADC） for a sensor interface, which can be integrated with the preceding sensor and the following controlling circuit. Without spending a special calibration phase or adding complicated functions, this circuit keeps a 12-bit resolution by trimming the capacitor array. Its merits of low power and small area make it suitable to be embedded in a power and cost sensitive system such as a battery-supplied sensor network node. The prototype 12-bit ADC is implemented by 0.5 m 2P3M CMOS technology, with the wide supply range of 2–5 V, its power consumption is only 300 A at a sampling speed of 200 kHz.展开更多
基金supported by National Natural Science Foundation of China (Grant No. 51005239)
文摘The mechanical balance process is the key process to eliminate the quadrature error and improve the performance of the cupped wave gyro. The conventional mechanical balance method for cupped wave gyro based on cup-wall trimming requires high control accuracy of trimming quantity, which increases the production cost and decreases the fabrication efficiency in large extent. However, it is hard to reach the high balance accuracy with the natural frequency split of mHz grade by using the conventional method. In this paper, the lumped mass dynamic model of the cupped wave gyro is built by discretization method, and the effects of different position trimming on the natural frequency are analyzed. It is pointed out that trimming off a tiny quantity of material from cup-wall causes large variation of the natural frequency is the main reason for the low accuracy of the conventional mechanical balance method. Then, a precision balance method for cupped wave gyro based on cup-bottom trimming is presented and the entire procedures of this method are given. The static balance process and dynamic balance process of the precision balance method are simulated by the finite element software. The simulation result shows that the precision balance method based on cup-bottom trimming brings less additional natural frequency split in the static balance process, minimizes the natural frequency split to mHz grade and rectify the angle of mode offset to 0.1° grade in the dynamic balance process, furthermore, the method decreases the requirement for control accuracy of trimming quantity evidently. The research work provides references for structure optimization design and balance process plan of the cupped wave gyro.
基金supported by a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions,China(PAPD).
文摘Airborne pulse Doppler radar is a key threat to the military helicopter,and assessing the stealth performance of helicopter against airborne early warning radar is helpful to the helicopter’s stealth design and operational planning.In this paper,the Shooting and Bouncing Ray(SBR)and Uniform Theory of Diffraction(UTD)based high-frequency algorithms are used to calculate the Radar Cross Section(RCS)of helicopter,and the radar range equations are used to evaluate the stealth performance.In order to account for the effects of rotor flapping motions during actual flight,the aerodynamics model of whole helicopter is established and the attitudes and controls of helicopter at different flight states are trimmed and input into the RCS calculation module.The effects of helicopter flight speed,flying direction and operational environment on radar stealth performance are studied in focus.It is demonstrated by the results that the trimming control does have a great influence of more than 5 dB on the RCS of helicopter,and the introduction of the trim calculation brings the helicopter’s returns calculation closer to the reality.Variations in flight speed lead to the changes in the stealth performance of helicopter against Early Warning Aircraft(EWA),and the helicopter flight speed can be planned according to the operational requirements to minimize exposure distance or exposure time.Variations in flying direction mainly affect the detection properties of helicopter returns,and flying in the same direction with EWA usually gives the helicopter better low-observability than flying head-on.Variations in operational environment mainly affect the radar detection performance and the sensitivity of the detection performance to external factors;the same amount of change in some external factor causes a different amount of change in the helicopter’s detectability in different environments.
基金Project supported by the National Natural Science Foundation of China(Grant No.61027007)
文摘In this paper, we introduce a z-axis quartz gyroscope using a double-H tuning fork, which has a high sensitivity. However, it also causes a large mechanical quadrature error. The laser trimming method is used to suppress this error at quartz level. The trimming law is obtained through the finite element method （FEM）. A femtosecond laser processing system is used to trim the gold balancing masses on the beams, and experimental results are basically consistent with the simulated ones. The mechanical quadrature error is suppressed by 96%, from 26.3° s-1 to 1.1° s-1. Nonlinearity changes from 1.48% to 0.30%, angular random walk （ARW） is reduced from 2.19° h-1/2 to 1.42° h-1/2, and bias instability is improved by a factor of 7.7, from 197.6° h-1 to 25.4° h-1.
基金This project is supported by National Natural Science Foundation of China (No.19832020)Provincial Natural Science Foundation of Jilin (No.20000519)
文摘Based on the elastic-plastic large deformation finite element formulation as well as the shell element combined discrete Kirchhoff theoretical plate element (DKT) with membrane square element, deep-drawing bending springback of typical U-pattern is studied. At the same time the springback values of the drawing of patterns' unloading and trimming about the satellite aerial reflecting surface are predicted and also compared with those of the practical punch. Above two springbacks all obtain satisfactory results, which provide a kind of effective quantitative pre-prediction of springback for the practical engineers.
文摘AIM:To evaluate the efficacy and safety of endoscopic removal and trimming of self-expandable metallic stents(SEMS).METHODS:All SEMS had been placed for distal biliary strictures.Twenty-seven endoscopic procedures were performed in 19 patients in whom SEMS(one uncovered and 18 covered) removal had been attempted,and 8 patients in whom stent trimming using argon plasma coagulation(APC) had been attempted at Tokyo Medical University Hospital.The APC settings were:voltage 60-80 W and gas flow at 1.5 L/min.RESULTS:The mean stent indwelling period for all patients in whom stent removal had been attempted was 113.7 ± 77.6 d(range,8-280 d).Of the 19 patients in whom removal of the SEMS had been attempted,the procedure was successful in 14(73.7%) without procedure-related adverse events.The indwelling period in the stent removable group was shorter than that in the unremovable group(94.9 ± 71.5 d vs 166.2 ± 76.2 d,P = 0.08).Stent trimming was successful for all patients with one minor adverse event consisting of self-limited hemorrhage.Trimming time ranged from 11 to 16 min.CONCLUSION:Although further investigations on larger numbers of cases are necessary to accumulate evidence,the present data suggested that stent removal and stent trimming is feasible and effective for stent-related complications.
基金supported by the National Natural Science Foundation of China(31072023)the National Agricultural Science and Technology Achievements Transformation Foundation of China(2009GB2D000218)as well as the Earmarked Fund for Modern Agro-Industry Technology Research System,China(CARS-41-K04)
文摘Beak trimming was a part of routine husbandry for poultry industry,which was the most efficient and economic way to reduce the incidence of cannibalism.However,the controversy about young chicken trimming still exits and it was drawing more concern recently along with the popular of animal behavior and welfare theory.To evaluate the influence of beak trimming on young chicken spleen development and find the key regulators of the spleen development,in this study,the electron microscope technique,flow cytometry and immunohistochemical techniques were used to investigate the effects of beak trimming stress on the spleen development.The result of electronic microscope showed that significant stress response could be found in chicken spleen cells after beak trimming.Cell volume became larger,chromatin of cell nuclear agglutinated conglobation,cytoplasm formed more vacuole,and mitochondria emerged vacuolization phenomenon in splenic lymphocyte after beak trimming.From the flow cytometry,the lymphocyte of spleen in the control group and experimental group were mainly in G1 phase,and the remaining small amount was in S and M phases.Of interest,the number of the lymphocyte which are in G1 phase within immune organ in the experimental group were more than that in the control group,but the number of cells in S and M phases were less than that in the control group.And beak trimming decreased the lymphocytes proliferation index of spleen.Inmmuohistochemical result showed that the beak trimming stress did not affect the expression sites of two apoptosis-related genes,Bcl-2 and Bax,in the spleen.But the expression level of Bcl-2 decreased while Bax increased in chicken immune organs after beak trimming.Furthermore,the beak trimming increased spleen cell apoptosis with a time-dependant style.Our findings may make a contribution to the active precaution of stress response.
文摘Mangrove forests in southern Iran are of high ecological and economic importance.These forests are being threatened because of uncontrolled harvesting to provide fodder for livestock.The objective of this study is to provide recommendations for appropriate harvesting intensities by quantifying the effect of different harvesting intensities on vegetative and vigor characteristics of mangrove trees.This study was conducted using a randomized complete block design comprising four treatments(10.00%,20.00%,and 30.00% trimming,along with a control)replicated three times.Vegetative characteristics were measured before and after trimming(five-year period)and analyzed using generalized linear model statistical analysis.The growths of the average diameter of canopy,canopy area,canopy volume,canopy height,tree height,and collar diameter in the control treatment were all significantly higher than those in the trimming treatments.In addition,there was a decreasing trend in leaf fresh and dry mass,leaf area index,total area of canopy leaves,and health status of tree in the trimming treatments.For example,the percentage change in fresh and dry leaf mass in the control treatment was positive(29.87% and 38.31%,respectively),whereas the trimming treatments of 10.00%,20.00% and 30.00% had negative effects(-7.01% and -4.79%,-11.32% and -14.30%,and -15.84% and -17.29%,respectively).In addition,the changes in leaf area index in the control(4.95%)and 30.00% trimming(-24.57%)treatments were the highest and lowest,respectively.The percentage change in soil organic matter in the control,10.00%,20.00%,and 30.00% treatments were 22.94%,-9.90%,-16.91%,and -18.68%,respectively.The study demonstrated that gray mangrove trees were highly sensitive to canopy trimming,with even minimal trimming intensities negatively affecting vegetative growth and soil organic matter.Therefore,it is recommended that cutting and trimming of mangrove trees should be prevented even at low intensity to preserve mangrove ecosystem health and resilience against environmental stressors.
基金financially supported by the Strategic Pilot Project of the Chinese Academy of Sciences-Class A(No.XDA0330302)the National Natural Science Foundation of China(Nos.62374183 and 62304247)the 2021 Jilin Province Science and Technology Department Key R&D Projects(No.20210201031GX)。
文摘In order to effectively remove the residual Ge atoms at the surface of channel and improve the interfacial characteristic of gate-all-around(GAA)Si nanosheet field effect transistors,a low-temperature atomic-level trimming approach using ammonia peroxide water mixture(APM)solution treatment followed by diluted hydrofluoric acid is proposed and carried out.The capacitor samples with SiGe epitaxy layer,similar thermal budget and channel release process were fabricated using advanced high-k/metal-gate.An 83%reduction in surface roughness at atomic level is obtained by increasing APM treatment time.Moreover,there are 99.45% reduction in the interface state density(D_(it))and 96.8%leakage reduction in current density(J_(g))after APM treatment,indicating a promising method for future GAA NSFET performance optimization.
基金supported by the Key Projects of the National Natural Science Foundation of China(51935013,52205613)the Regional Innovative Development Joint Funds of the National Natural Science Foundation of China(U21A20505).
文摘The frequency mismatch caused by material defects and geometric errors during the manufacturing process is a critical factor limiting the performance of micro-shell resonator gyroscope(MSRG).Compared with other MEMS gyroscopes,the frequency mismatch of MSRG can fundamentally be reduced by mechanical trimming.However,it is challenged by the precise characterization.Previous studies about the characterization of frequency mismatch are almost based on frequency spectrum analysis and sweeping,which can only meet the requirement of trimming efficiency of over 100 mHz,limited by the signal noise and temperature drift.In this paper,a novel characterization method of frequency mismatch based on the quadrature-control force under the self-precession mode is proposed to meet the requirement of high-precision mechanical trimming.Furthermore,the phase errors which affect the accuracy of characterization is analyzed,and methods for the correction of phase errors are proposed.Based on this characterization method,0.32 mHz frequency mismatch of micro-shell resonator is achieved by mechanical trimming,which is the best-reported performance for mechanical trimming of MEMS gyroscopes so far.More importantly,this novel characterization method can be applied for other kinds of resonators which can be mechanical trimmed.
基金supported by the National Natural Science Foundation for Young Scholars of China(No.52005077)the Natural Science Foundation of Liaoning Province(No.2022-BS090)the Fundamental Research Funds for the Central Universities(No.DUT23RC(3)010).
文摘This study proposes a novel tool wear model for the edge trimming process of carbon fiber-reinforced plasticities(CFRPs).The main innovation is that the model considers the actual wear state of both the planar flank face and the semicylindrical cutting edge.In addition,for the whole wear process,the model illustrates the dynamic wear condition by introducing a varying wear coefficient determined by the instantaneous force‒temperature condition and relative movement distance.The analytical results of the tool wear law suggest that cutting edge wear depends on tool nose rigidity and the practical contact distance with the CFRP workpiece mainly.To suppress cutting edge wear,reducing the rake angle and flank angle to improve rigidity and selecting a low spindle speed and high feed rate to decrease the practical cutting distance are recommended.The wear of the flank face is mainly determined by the flank angle and bouncing back height of the machined surface.To reduce its wear,a large flank angle,high spindle speed,and low feed rate are recommended.Since the strategies for reducing the wear of the cutting edge and flank faces are contradictory,to reduce tool wear more effectively,reducing cutting-edge wear is prioritized.
基金supported by the National Natural Science Foundation of China(62204261,51935013 and 52075540).
文摘This study presents a scheme for the identification and trimming of the first three harmonics of mass defects in micro hemispherical resonators(MHRs),aiming to refine their mass balancing techniques.Given the manufacturing and structural uniqueness of MHRs,a multimodal elastic electrode substrate is designed to respond to the first three harmonics.Configured as cantilever beams with a load platform,this substrate forms an identification assembly with the MHR.The radial eccentric forces generated by the 1st and 3rd harmonics in the MHR can excite the swing modes of the assembly,while the axial force generated by the 2nd harmonic can induce axial mode vibrations along the Z-axis.A method is proposed to decompose the vibration information of the elastic electrode substrate into doublecycle,single-cycle,and offset components under the N=2 modes,enabling the extraction of swing mode and Z-axis translational mode response signals and the retro-calculation of the first three harmonics.Finite element simulation,based on a model of the identification assembly,validates the proposed scheme by simulating the identification and trimming process.Subsequently,an identification assembly sample is fabricated and subjected to identification and trimming of the first three harmonics using a laser vibrometer and femtosecond laser ablation process.After multiple iterations,the first three harmonics are reduced by 92.8%,89.3%,and 75.5%,respectively,effectively suppressing the swing modes and axial translation modes induced by unbalanced mass.
基金Project (No.2008ZX01020-001) supported by the National Science and Technology Major Project,China
文摘A low temperature drift curvature-compensated complementary metal oxide semiconductor (CMOS) bandgap ref-erence is proposed.A dual-differential-pair amplifier was employed to add compensation with a high-order term of TlnT (T is the thermodynamic temperature) to the traditional 1st-order compensated bandgap.To reduce the offset of the amplifier and noise of the bandgap reference,input differential metal oxide semiconductor field-effect transistors (MOSFETs) of large size were used in the amplifier and to keep a low quiescent current,these MOSFETs all work in weak inversion.The voltage reference's temperature curvature has been further corrected by trimming a switched resistor network.The circuit delivers an output voltage of 3 V with a low dropout regulator (LDO).The chip was fabricated in Taiwan Semiconductor Manufacturing Company (TSMC)'s 0.35-μm CMOS process,and the temperature coefficient (TC) was measured to be only 2.1×10 6/°C over the temperature range of 40-125 °C after trimming.The power supply rejection (PSR) was 100 dB @ DC and the noise was 42 μV (rms) from 0.1 to 10 Hz.
基金We thank Kay Lee Pte Ltd Singapore for providing raw pork samples.
文摘In this research,the effects of heat treatment together with xylose and cysteine addition on the amino acid changes and volatile compound generation in non-enzymatic pork trimmings extract(NPE)or enzymatic pork trimmings hydrolysate(EPH)were studied.Enzymatic hydrolysis significantly increased the total amino acid content and provided necessary precursors for the thermal reactions.The addition of xylose assisted the browning process while the cysteine addition partially inhibited the formation of brown colour in both NPE and EPH.The addition of both cysteine and xylose significantly increased the formation of sulfur-containing volatile flavour compounds in EPH samples,but not in NPE samples.The characteristic“roasted meat”like aromatic volatile compounds,in particular,2-furfurylthiol,were only detected in EPH samples at 8.13 ng/mL,when both xylose(35 mg/mL)and cysteine(10 mg/mL)were added.
基金Engineering and Physical Sciences Research Council(EPSRC)(EP/L00044X/1,EP/M022757/1)Wolfson FoundationRoyal Society
文摘We demonstrate a novel high-accuracy post-fabrication trimming technique to fine-tune the phase of integrated Mach–Zehnder interferometers, enabling permanent correction of typical fabrication-based phase errors. The effective index change of the optical mode is 0.19 in our measurement, which is approximately an order of magnitude improvement compared to previous work with similar excess optical loss. Our measurement results suggest that a phase accuracy of 0.078 rad was achievable with active feedback control.
基金the National Key R&D Program of China(Grant No.2016YFB1102500)the Key R&D Project in Shaanxi Province(Grant No.2019ZDLGY01-07)the Science and Technology Program of Jiangsu Province,China(Grant No.SBK2019041271).
文摘Ceramic structural parts are one of the most widely utilized structural parts in the industry. However, they usually contain defects following the pressing process, such as burrs. Therefore, additional trimming is usually required, despite the deformation challenges and difficulty in positioning. This paper proposes an ultrafast laser processing system for trimming complex ceramic structural parts. Opto-electromechanical cooperative control software is developed to control the laser processing system. The trimming problem of the ceramic cores used in aero engines is studied. The regional registration method is introduced based on the iterative closest point algorithm to register the path extracted from the computer-aided design model with the deformed ceramic core. A zonal and layering processing method for three-dimensional contours on complex surfaces is proposed to generate the working data of high-speed scanning galvanometer and the computer numerical control machine tool, respectively. The results show that the laser system and the method proposed in this paper are suitable for trimming complex non-datum parts such as ceramic cores. Compared with the results of manual trimming, the method proposed in this paper has higher accuracy, efficiency, and yield. The method mentioned above has been used in practical application with satisfactory results.
基金supported by the National Natural Science Foundation of China(No.61204034)
文摘This work presented a trimming technique and algorithm applied in a capacitive successive approximation register（SAR） analog to digital converter（ADC） for a sensor interface, which can be integrated with the preceding sensor and the following controlling circuit. Without spending a special calibration phase or adding complicated functions, this circuit keeps a 12-bit resolution by trimming the capacitor array. Its merits of low power and small area make it suitable to be embedded in a power and cost sensitive system such as a battery-supplied sensor network node. The prototype 12-bit ADC is implemented by 0.5 m 2P3M CMOS technology, with the wide supply range of 2–5 V, its power consumption is only 300 A at a sampling speed of 200 kHz.
