The primary synchronization signal and the secondary synchronization signal are respectively used to fulfill the subframe and frame synchronization in the long term evolution （LTE） systems. Based on the assumption t...The primary synchronization signal and the secondary synchronization signal are respectively used to fulfill the subframe and frame synchronization in the long term evolution （LTE） systems. Based on the assumption that the channel frequency response of the primary synchronization signal symbol is nearly the same as that of the secondary synchronization symbol in frequency division duplex-LTE （FDD-LTE）, a new synchronization method is proposed. The frame synchronization success probability is simulated in different wireless channel models and the Mento-Carlo method is used in the simulation. Simulation results show that if the LMMSE channel estimation is adopted, the proposed method is robust at a low signal noise ratio （SNR） scenario and works well when cartier frequency offset and fast Fourier transform （FFT） window timing offset are considered in practical applications. The frame synchronization success probability can still exceed 99% with an SNR of 0 dB when the maximum Doppler shift is very large, which means that this robust frame synchronization method can be applicable in most mobile situations. Simulation results also show that the success probability of the proposed frame synchronization method is higher than that of the method which fulfills the frame synchronization through correlating the received secondary synchronization symbol with local sequences in practical applications.展开更多
With the aim of preventing iatrogenic shot trunk,stiffness and rotation deformity caused by long-term fixation with usual locked pedicle screw system,a new kind of slidable pedicle screw frame system was designed and ...With the aim of preventing iatrogenic shot trunk,stiffness and rotation deformity caused by long-term fixation with usual locked pedicle screw system,a new kind of slidable pedicle screw frame system was designed and fabricated to treat patients with spinal deformity in the growth period.The frame was composed of slidable and locked pedicle screws,cross-links and double rods.The middle part of double rods was fixed with locked pedicle screws and two ends of them were with slidable ones.The spine longitudinal and transverse growth was not limited.360 patients including 82 congenital scoliosis,110 idiopathic scoliosis,60 kyphosis,44 spinal fractures and 63 spinal tumors or tuberculosis were treated.The average pre-operative Cobb’s angle of scoliosis was 66.43°,post-operative one was 22.43°and lost 5°with average 14 months of following-up(6-37 months).The total longitudinal growth of adolescent spinal deformity was 86.4 cm(mean 0.9 cm).In conclusion,slidable pedicle screw frame system is successfully designed and fabricated,also stable and effective to correct the spinal deformities in adolescent growth period.The longitudinal and transverse spine growth of post-operation patients was not limited,and no complications such as stiffness,vertebrae rotation and crank shaft happened for post-operation patients.展开更多
The workpiece frames relative to each robot base frame should be known in advance for the proper operation of twin-robot nondestructive testing system. However, when two robots are separated from the workpieces, the t...The workpiece frames relative to each robot base frame should be known in advance for the proper operation of twin-robot nondestructive testing system. However, when two robots are separated from the workpieces, the twin robots cannot reach the same point to complete the process of workpiece frame positioning. Thus, a new method is proposed to solve the problem of coincidence between workpiece frames. Transformation between two robot base frames is initiated by measuring the coordinate values of three non-collinear calibration points. The relationship between the workpiece frame and that of the slave robot base frame is then determined according to the known transformation of two robot base frames, as well as the relationship between the workpiece frame and that of the master robot base frame. Only one robot is required to actually measure the coordinate values of the calibration points on the workpiece. This requirement is beneficial when one of the robots cannot reach and measure the calibration points. The coordinate values of the calibration points are derived by driving the robot hand to the points and recording the values of top center point（TCP） coordinates. The translation and rotation matrices relate either the two robot base frames or the workpiece and master robot. The coordinated are solved using the measured values of the calibration points according to the Cartesian transformation principle. An optimal method is developed based on exponential mapping of Lie algebra to ensure that the rotation matrix is orthogonal. Experimental results show that this method involves fewer steps, offers significant advantages in terms of operation and time-saving. A method used to synchronize workpiece frames in twin-robot system automatically is presented.展开更多
This paper presents the results of a parametric study of self-centering seismic retrofit schemes for reinforced concrete (RC) frame buildings. The self-centering retrofit system features flag-shaped hysteresis and min...This paper presents the results of a parametric study of self-centering seismic retrofit schemes for reinforced concrete (RC) frame buildings. The self-centering retrofit system features flag-shaped hysteresis and minimal residual deformation. For comparison purpose,an alternate seismic retrofit scheme that uses a bilinear-hysteresis retrofit system such as buckling-restrained braces (BRB) is also considered in this paper. The parametric study was carried out in a single-degree-of-freedom (SDOF) system framework since a multi-story building structure may be idealized as an equivalent SDOF system and investigation of the performance of this equivalent SDOF system can provide insight into the seismic response of the multi-story building. A peak-oriented hysteresis model which can consider the strength and stiffness degradation is used to describe the hysteretic behavior of RC structures. The parametric study involves two key parameters -the strength ratio and elastic stiffness ratio between the seismic retrofit system and the original RC frame. An ensemble of 172 earthquake ground motion records scaled to the design basis earthquake in California with a probability of exceedance of 10% in 50 years was constructed for the simulation-based parametric study. The effectiveness of the two seismic retrofit schemes considered in this study is evaluated in terms of peak displacement ratio,peak acceleration ratio,energy dissipation demand ratio and residual displacement ratio between the SDOF systems with and without retrofit. It is found from this parametric study that RC structures retrofitted with the self-centering retrofit scheme (SCRS) can achieve a seismic performance level comparable to the bilinear-hysteresis retrofit scheme (BHRS) in terms of peak displacement and energy dissipation demand ratio while having negligible residual displacement after earthquake.展开更多
A flame length optimization scheme is proposed for multi-antenna downlink systems to guarantee diverse delay- bound violation probability constraints. Due to the difficulties of extracting the quality of service （QoS...A flame length optimization scheme is proposed for multi-antenna downlink systems to guarantee diverse delay- bound violation probability constraints. Due to the difficulties of extracting the quality of service （QoS） metrics from the conventional physical-layer channel models, the link-layer models named effective bandwidth and effective capacity are applied to statistically characterize the source traffic patterns and the queuing service dynamics. With these link-layer models, the source traffic process and the channel service process are mapped to certain QoS parameters. The packet delay-bound violation probability constraints are converted into minimum data rate constraints and the optimization problem is thus formulated into simultaneous inequalities. With the assumption of ergodic block-fading channels, the optimal frame lengths of single-user and multiuser systems are calculated respectively by numerical iterative methods. Theoretical analyses and simulation results show that the given delay-bound violation probability constraints are well satisfied with the optimal frame length.展开更多
This paper presents the experimental and numerical studies conducted on a steel column and a steel frame structure using free vibration analysis.The effects of damages on structures were investigated,which were simula...This paper presents the experimental and numerical studies conducted on a steel column and a steel frame structure using free vibration analysis.The effects of damages on structures were investigated,which were simulated by introducing multiple cracks at different locations in the experimental and numerical models.The acceleration responses of the test models,were recorded through an accelerometer,and were used to calibrate the numerical models developed in finite element based software.Modal frequencies of damaged and undamaged structures were compared and analyzed,to derive relationships for damaged and undamaged structures’frequencies in terms of crack depth.It was found that,due to the presence of cracks,the mechanical properties of a structure changes,whereby,the modal frequencies decrease.An approximately linear trend was observed for the frequency decrease with the increase in crack depth,which was also confirmed by the numerical models.The derived relationships were extended to further develop a mechanics-based damage scale for steel structures,to help facilitate structural health monitoring and screening of vulnerable structures.展开更多
A model system was employed to study the operating conditions and primary parameters of enzymic hydrolysis of cod proteins. Pancreatin, papain, and bromelain were used to hydrolyse minced cod fillets under controlled ...A model system was employed to study the operating conditions and primary parameters of enzymic hydrolysis of cod proteins. Pancreatin, papain, and bromelain were used to hydrolyse minced cod fillets under controlled conditions and with the rate of hydrolysis being continually monitored via both the pH-stat and TNBS method. The two methods were compared and evaluated. The rate of protein solubilisation was plotted against the degree of hydrolysis (DH). Dry fish protein hydrolysate (FPH) powders having short, medium and high degrees of hydrolysis (DH of approximately 8%, 11% and 16% respectively) were produced and analysed for their molecular weight distribution, using size exclusion chromatography. Almost complete protein solubilisation (75 g soluble protein per kg hydrolysis solution) could be achieved within an hour, at 40oC, at 1% enzyme/substrate ratio (w/w) with papain and bromelain. The pH-stat was found capable of continuously following the rate of hydrolysis but only at low DH. The TNBS could be accurately used even at high DH to estimate the percentage of the peptide bonds cleaved, but required chemical analysis of withdrawn samples.展开更多
Frame and frequency synchronization are essential for orthogonal frequency division multiplexing （OFDM） systems. The frame offset owing to incorrect start point position of the fast Fourier transform （FFT） window,...Frame and frequency synchronization are essential for orthogonal frequency division multiplexing （OFDM） systems. The frame offset owing to incorrect start point position of the fast Fourier transform （FFT） window, and the carrier frequency offset （CFO） due to Doppler frequency shift or the frequency mismatch between the transmitter and receiver oscil ators, can bring severe inter-symbol interference （ISI） and inter-carrier interference （ICI） for the OFDM system. Relying on the relatively good correlation charac-teristic of the pseudo-noise （PN） sequence, a joint frame offset and normalized CFO estimation algorithm based on PN preamble in time domain is developed to realize the frame and frequency synchronization in the OFDM system. By comparison, the perfor-mances of the traditional algorithm and the improved algorithm are simulated under different conditions. The results indicate that the PN preamble based algorithm both in frame offset estimation and CFO estimation is more accurate, resource-saving and robust even under poor channel condition, such as low signal-to-noise ratio （SNR） and large normalized CFO.展开更多
The first integrals and their conditions of existence for variable massnonholonomic system in noninertial relerence frames are obtained,and the canonicalequations and the variation equations of the system are extended...The first integrals and their conditions of existence for variable massnonholonomic system in noninertial relerence frames are obtained,and the canonicalequations and the variation equations of the system are extended. It is proved that using the first integral we can construct the integral invariant of the system.Finally,a series of deductions and an example are given.展开更多
This paper establishes the integral theory for the dynamics of nonlinear nonholonomic system in noninertial reference frame. Firstly, based on the Routh equation of the relative motion of nonlinear nonholonomic system...This paper establishes the integral theory for the dynamics of nonlinear nonholonomic system in noninertial reference frame. Firstly, based on the Routh equation of the relative motion of nonlinear nonholonomic system gives the first integral of the system. Secondly, by using cyclic integral or energy integral reduces the order of the equation and obtains generalized Routh equation and Whittaker equation respectively. Thirdly, derives canonical equation and variation equation and by using the first integral constructs integral invariant. And then, establishes the basic integral variants and the integral invariant of Poincare-Cartan type. Finally, we give a series of deductions.展开更多
Viscoelastic damper is an effective passive damping device,which can reduce the seismic response of the structure by increasing the damping and dissipating the vibration energy of structures.It has a wide application ...Viscoelastic damper is an effective passive damping device,which can reduce the seismic response of the structure by increasing the damping and dissipating the vibration energy of structures.It has a wide application prospect in actual structural vibration control because of simple device and economical material.In view of the poor seismic behaviors of assembled frame structure connections,various energy dissipation devices are proposed to improve the seismic performance.The finite element numerical analysis method is adopted to analyze relevant energy dissipation structural parameters.The response spectrum of a 7-story assembled frame structure combined the ordinary steel support,ordinary viscoelastic damper,and viscoelastic damper with displacement amplification device is analyzed.The analysis results show that the mechanical behavior of assembled frame structure with ordinary steel supports are not significantly different from those without energy dissipation devices.The assembled frame structure with viscoelastic damper has better seismic performance and energy dissipation,especially for the viscoelastic damper with displacement amplification devices.The maximum value of inter-story displacement angle decreases by 32.24%;the maximum floor displacement decreases by 31.91%,and the base shear decreases by 13.62%compared with the assembled frame structures without energy dissipation devices.The results show that the seismic fortification ability of the structure is significantly improved,and the overall structure is more uniformly stressed.The damping structure with viscoelastic damper mainly reduces the dynamic response of the structure by increasing the damping coefficient,rather than by changing the natural vibration period of the structure.This paper provides an effective theoretical basis and reference for improving the energy dissipation system and the seismic performance of assembled frame structures.展开更多
Pilot contamination limits the performance of massive multiple-input multiple-output（MIMO） system severely due to the degraded channel estimation. An efficient way to solve this problem in time division duplex（TDD...Pilot contamination limits the performance of massive multiple-input multiple-output（MIMO） system severely due to the degraded channel estimation. An efficient way to solve this problem in time division duplex（TDD） wireless system is shifting the location of pilots in time frames used in neighboring cells. However, the shifted frame structure has only been studied in MIMO system with the ideal independent and identically distributed（i.i.d.） channel coefficients. In this paper, the shifted frame structure is studied in a measured channel with a large number of antennas for a certain class of channel fading statistics. To deal with the high inter-cell interference caused by the shifted frame structure in such a measured channel condition, we propose a scenario with a covariance-aided channel estimator. This scenario shows that pilot contamination can be solved and the high inter-cell interference can be made to vanish asymptotically with the number of antennas. The key of the interference rejection is obtaining the precise condition on the second order statistics for the desired and interference signals. The most significant information of the second order statistics comes from two parts, one is the channel state information（CSI） among the base stations（BSs）, the other comes from the estimated information exchanged by the BSs, which depicts the channel between the BSs and the users. The simulations give powerful results of the interference rejection and the achievable rate promotion.展开更多
Frame detection is important in burst communication systems for its contribu- tions in frame synchronization. It locates the information bits in the received data stream at receivers. To realize frame detection in the...Frame detection is important in burst communication systems for its contribu- tions in frame synchronization. It locates the information bits in the received data stream at receivers. To realize frame detection in the presence of additive white Gaussian noise （AWGN） and frequency offset, a constant false alarm rate （CFAR） detector is proposed through exploitation of cyclic autocorrelation feature implied in the preamble. The frame detection can be achieved prior to bit timing recovery. The threshold setting is independent of the signal level and noise level by utilizing CFAR method. Mathematical expressions is derived in AWGN channel by considering the probability of false alarm and probability of detection, separately. Given the probability of false alarm, the mathematical relationship between the frame detection performance and EJNo of received signals is established. Ex- perimental results are also presented in accor- dance with analysis.展开更多
The new variational principle of Gauss's form of nonlinear nonholonomic nonpotential system relative to non-inertial reference frame is established by constructing generalized inertial potentials. Naether's th...The new variational principle of Gauss's form of nonlinear nonholonomic nonpotential system relative to non-inertial reference frame is established by constructing generalized inertial potentials. Naether's theorem and Naether's inverse theorem of the system above is presented and proved. Finally, one example is given to illustrate the application.展开更多
We investigate the dynamics of measurement-induced disturbance(MID) for a qubit-qutrit system in noninertial frames under various multi-local decoherence channels(i.e.,dephasing,phase-flip,bit-(trit-) flip,bit-(trit-)...We investigate the dynamics of measurement-induced disturbance(MID) for a qubit-qutrit system in noninertial frames under various multi-local decoherence channels(i.e.,dephasing,phase-flip,bit-(trit-) flip,bit-(trit-) phase-flip,and depolarizing channels).We find that,for any acceleration,the MID can decay in a monotonic way to zero or to a nonzero steady value(i.e.,residual MID exists).Consequently,no sudden death of the MID occurs,which is different from entanglement.展开更多
This paper presents the generalized principles of least action of variable mass nonholonomic nonconservative system in noninertial reference frame, proves the equivalence between Holder form and Suslov form, and then ...This paper presents the generalized principles of least action of variable mass nonholonomic nonconservative system in noninertial reference frame, proves the equivalence between Holder form and Suslov form, and then obtains differential equations of motion of variable mass nonholonomic nonconservative system in noninertial reference frame.展开更多
A double system of exponents with piecewise continuous complex-valued coefficients are considered. Under definite conditions on the coefficients the frame property of this system in Lebesgue spaces of functions is inv...A double system of exponents with piecewise continuous complex-valued coefficients are considered. Under definite conditions on the coefficients the frame property of this system in Lebesgue spaces of functions is investigated. Such systems arise in the spectral problems for discontinuous differential operators.展开更多
The prevention of common pig diseases depends on the experience of veterinarian greatly due to complexity of piggery pestilence. The expert system for the prophylaxis and treatment of common pig diseases is able to ma...The prevention of common pig diseases depends on the experience of veterinarian greatly due to complexity of piggery pestilence. The expert system for the prophylaxis and treatment of common pig diseases is able to make the complex task more effective. The construction and im- plementation of this expert system is based on the bottleneck problems of the traditional expert system knowledge acquisition and the frame descrip- tion of symptoms of common pig diseases, used the knowledge project method and technology, and combined the uncertainty inference and dispel- ling strategy of matching conflict and technology of multimedia. This expert system is used to imitate expert thinking and supplement or substitute for veterinary experts to guide the prophylaxis and treatment of common pig diseases. The overall structure, knowledge expression, inference mecha- nism and system realization would be expounded emphatically.展开更多
Papain was used to hydrolyse fish frames under controlled conditions at a batch-pilot plant scale- process, for the production of fish protein hydrolysates (FPH). Mass balance calculations were carried out so that the...Papain was used to hydrolyse fish frames under controlled conditions at a batch-pilot plant scale- process, for the production of fish protein hydrolysates (FPH). Mass balance calculations were carried out so that the rate of hydrolysis, rate of protein solubilisation and yields could be estimated. Almost complete hydrolysis could be achieved in 1 hour, at 40oC, with no pH adjustment, at 0.5% (5 g.kg-1) enzyme to substrate ratio (E/S, were S is Kjeldahl protein) using whole fish frames (including heads and flaps). This was achieved both with the addition of water (1/1 to 2/1 frames/water) but more importantly from commercial considerations without the initial addition of water (after mincing of the fish material). The degree of protein solubilisation ranged between 71% - 86% w/w. Four different processes are described, namely: 1) a soluble spray-dried FPH powder 2) a liquid FPH 3) a partly soluble, spray dried FPH powder and 4) a crude, drum-dried protein for animal consumption. The amino acid profile of the FPH was identical to that of the parent substrate (fish frames).展开更多
This paper puts forward a new drafting system of the rubbed roving frame, which consists of a nine-link gear, two slipping gears. It has brought forward a new design method of the nine-link gear and the slipping gears...This paper puts forward a new drafting system of the rubbed roving frame, which consists of a nine-link gear, two slipping gears. It has brought forward a new design method of the nine-link gear and the slipping gears, and set up approximate formulas for modification coefficients of gears for the first time. And the principles of transmitting rate designing for the system are given. The calculating results demonstrate that the new design method satisfies the demands of processing technology. This mechanism has been used successfully in the kind of rubbed roving frame.展开更多
文摘The primary synchronization signal and the secondary synchronization signal are respectively used to fulfill the subframe and frame synchronization in the long term evolution （LTE） systems. Based on the assumption that the channel frequency response of the primary synchronization signal symbol is nearly the same as that of the secondary synchronization symbol in frequency division duplex-LTE （FDD-LTE）, a new synchronization method is proposed. The frame synchronization success probability is simulated in different wireless channel models and the Mento-Carlo method is used in the simulation. Simulation results show that if the LMMSE channel estimation is adopted, the proposed method is robust at a low signal noise ratio （SNR） scenario and works well when cartier frequency offset and fast Fourier transform （FFT） window timing offset are considered in practical applications. The frame synchronization success probability can still exceed 99% with an SNR of 0 dB when the maximum Doppler shift is very large, which means that this robust frame synchronization method can be applicable in most mobile situations. Simulation results also show that the success probability of the proposed frame synchronization method is higher than that of the method which fulfills the frame synchronization through correlating the received secondary synchronization symbol with local sequences in practical applications.
文摘With the aim of preventing iatrogenic shot trunk,stiffness and rotation deformity caused by long-term fixation with usual locked pedicle screw system,a new kind of slidable pedicle screw frame system was designed and fabricated to treat patients with spinal deformity in the growth period.The frame was composed of slidable and locked pedicle screws,cross-links and double rods.The middle part of double rods was fixed with locked pedicle screws and two ends of them were with slidable ones.The spine longitudinal and transverse growth was not limited.360 patients including 82 congenital scoliosis,110 idiopathic scoliosis,60 kyphosis,44 spinal fractures and 63 spinal tumors or tuberculosis were treated.The average pre-operative Cobb’s angle of scoliosis was 66.43°,post-operative one was 22.43°and lost 5°with average 14 months of following-up(6-37 months).The total longitudinal growth of adolescent spinal deformity was 86.4 cm(mean 0.9 cm).In conclusion,slidable pedicle screw frame system is successfully designed and fabricated,also stable and effective to correct the spinal deformities in adolescent growth period.The longitudinal and transverse spine growth of post-operation patients was not limited,and no complications such as stiffness,vertebrae rotation and crank shaft happened for post-operation patients.
基金Supported by International S&T Cooperation Program of China(Grant No.2012DFA70260)High-end CNC Machine and Basic Manufacturing Equipment of Chinese Key National Science and Technology(Grant No.2011ZX04014-081)
文摘The workpiece frames relative to each robot base frame should be known in advance for the proper operation of twin-robot nondestructive testing system. However, when two robots are separated from the workpieces, the twin robots cannot reach the same point to complete the process of workpiece frame positioning. Thus, a new method is proposed to solve the problem of coincidence between workpiece frames. Transformation between two robot base frames is initiated by measuring the coordinate values of three non-collinear calibration points. The relationship between the workpiece frame and that of the slave robot base frame is then determined according to the known transformation of two robot base frames, as well as the relationship between the workpiece frame and that of the master robot base frame. Only one robot is required to actually measure the coordinate values of the calibration points on the workpiece. This requirement is beneficial when one of the robots cannot reach and measure the calibration points. The coordinate values of the calibration points are derived by driving the robot hand to the points and recording the values of top center point（TCP） coordinates. The translation and rotation matrices relate either the two robot base frames or the workpiece and master robot. The coordinated are solved using the measured values of the calibration points according to the Cartesian transformation principle. An optimal method is developed based on exponential mapping of Lie algebra to ensure that the rotation matrix is orthogonal. Experimental results show that this method involves fewer steps, offers significant advantages in terms of operation and time-saving. A method used to synchronize workpiece frames in twin-robot system automatically is presented.
基金Univeristy of Maryland,Start-up Grant to the First Author
文摘This paper presents the results of a parametric study of self-centering seismic retrofit schemes for reinforced concrete (RC) frame buildings. The self-centering retrofit system features flag-shaped hysteresis and minimal residual deformation. For comparison purpose,an alternate seismic retrofit scheme that uses a bilinear-hysteresis retrofit system such as buckling-restrained braces (BRB) is also considered in this paper. The parametric study was carried out in a single-degree-of-freedom (SDOF) system framework since a multi-story building structure may be idealized as an equivalent SDOF system and investigation of the performance of this equivalent SDOF system can provide insight into the seismic response of the multi-story building. A peak-oriented hysteresis model which can consider the strength and stiffness degradation is used to describe the hysteretic behavior of RC structures. The parametric study involves two key parameters -the strength ratio and elastic stiffness ratio between the seismic retrofit system and the original RC frame. An ensemble of 172 earthquake ground motion records scaled to the design basis earthquake in California with a probability of exceedance of 10% in 50 years was constructed for the simulation-based parametric study. The effectiveness of the two seismic retrofit schemes considered in this study is evaluated in terms of peak displacement ratio,peak acceleration ratio,energy dissipation demand ratio and residual displacement ratio between the SDOF systems with and without retrofit. It is found from this parametric study that RC structures retrofitted with the self-centering retrofit scheme (SCRS) can achieve a seismic performance level comparable to the bilinear-hysteresis retrofit scheme (BHRS) in terms of peak displacement and energy dissipation demand ratio while having negligible residual displacement after earthquake.
基金The National Science and Technology M ajor Project(No.2012ZX03004005-003)the National Natural Science Foundation of China(No.61171081,61201175)the Research Fund of National M obile Communications Research Laboratory of Southeast University(No.2014A03)
文摘A flame length optimization scheme is proposed for multi-antenna downlink systems to guarantee diverse delay- bound violation probability constraints. Due to the difficulties of extracting the quality of service （QoS） metrics from the conventional physical-layer channel models, the link-layer models named effective bandwidth and effective capacity are applied to statistically characterize the source traffic patterns and the queuing service dynamics. With these link-layer models, the source traffic process and the channel service process are mapped to certain QoS parameters. The packet delay-bound violation probability constraints are converted into minimum data rate constraints and the optimization problem is thus formulated into simultaneous inequalities. With the assumption of ergodic block-fading channels, the optimal frame lengths of single-user and multiuser systems are calculated respectively by numerical iterative methods. Theoretical analyses and simulation results show that the given delay-bound violation probability constraints are well satisfied with the optimal frame length.
文摘This paper presents the experimental and numerical studies conducted on a steel column and a steel frame structure using free vibration analysis.The effects of damages on structures were investigated,which were simulated by introducing multiple cracks at different locations in the experimental and numerical models.The acceleration responses of the test models,were recorded through an accelerometer,and were used to calibrate the numerical models developed in finite element based software.Modal frequencies of damaged and undamaged structures were compared and analyzed,to derive relationships for damaged and undamaged structures’frequencies in terms of crack depth.It was found that,due to the presence of cracks,the mechanical properties of a structure changes,whereby,the modal frequencies decrease.An approximately linear trend was observed for the frequency decrease with the increase in crack depth,which was also confirmed by the numerical models.The derived relationships were extended to further develop a mechanics-based damage scale for steel structures,to help facilitate structural health monitoring and screening of vulnerable structures.
文摘A model system was employed to study the operating conditions and primary parameters of enzymic hydrolysis of cod proteins. Pancreatin, papain, and bromelain were used to hydrolyse minced cod fillets under controlled conditions and with the rate of hydrolysis being continually monitored via both the pH-stat and TNBS method. The two methods were compared and evaluated. The rate of protein solubilisation was plotted against the degree of hydrolysis (DH). Dry fish protein hydrolysate (FPH) powders having short, medium and high degrees of hydrolysis (DH of approximately 8%, 11% and 16% respectively) were produced and analysed for their molecular weight distribution, using size exclusion chromatography. Almost complete protein solubilisation (75 g soluble protein per kg hydrolysis solution) could be achieved within an hour, at 40oC, at 1% enzyme/substrate ratio (w/w) with papain and bromelain. The pH-stat was found capable of continuously following the rate of hydrolysis but only at low DH. The TNBS could be accurately used even at high DH to estimate the percentage of the peptide bonds cleaved, but required chemical analysis of withdrawn samples.
基金supported by the National Natural Science Foundation of China(6130110561102069)+2 种基金the China Postdoctoral Science Foundation Funded Project(2013M531351)the Nanjing University of Aeronautics and Astronautics Founding(NN2012022)the Open Fund of Graduate Innovated Base(Laboratory)for the Nanjing University of Aeronautics and Astronautics(KFJJ120219)
文摘Frame and frequency synchronization are essential for orthogonal frequency division multiplexing （OFDM） systems. The frame offset owing to incorrect start point position of the fast Fourier transform （FFT） window, and the carrier frequency offset （CFO） due to Doppler frequency shift or the frequency mismatch between the transmitter and receiver oscil ators, can bring severe inter-symbol interference （ISI） and inter-carrier interference （ICI） for the OFDM system. Relying on the relatively good correlation charac-teristic of the pseudo-noise （PN） sequence, a joint frame offset and normalized CFO estimation algorithm based on PN preamble in time domain is developed to realize the frame and frequency synchronization in the OFDM system. By comparison, the perfor-mances of the traditional algorithm and the improved algorithm are simulated under different conditions. The results indicate that the PN preamble based algorithm both in frame offset estimation and CFO estimation is more accurate, resource-saving and robust even under poor channel condition, such as low signal-to-noise ratio （SNR） and large normalized CFO.
文摘The first integrals and their conditions of existence for variable massnonholonomic system in noninertial relerence frames are obtained,and the canonicalequations and the variation equations of the system are extended. It is proved that using the first integral we can construct the integral invariant of the system.Finally,a series of deductions and an example are given.
基金Project supported by the Natural Science Foundation of He’nan Province
文摘This paper establishes the integral theory for the dynamics of nonlinear nonholonomic system in noninertial reference frame. Firstly, based on the Routh equation of the relative motion of nonlinear nonholonomic system gives the first integral of the system. Secondly, by using cyclic integral or energy integral reduces the order of the equation and obtains generalized Routh equation and Whittaker equation respectively. Thirdly, derives canonical equation and variation equation and by using the first integral constructs integral invariant. And then, establishes the basic integral variants and the integral invariant of Poincare-Cartan type. Finally, we give a series of deductions.
基金supported by Foundation of Henan Educational Committee(20A560004,J.Z.)Foundation of Henan Science and Technology Project(182102311086,Y.W.)Foundation for University Key Teacher(YCJQNGGJS201901,J.Z.,YCJXSJSDTR201801,Y.W.,Henan University of Urban Construction).
文摘Viscoelastic damper is an effective passive damping device,which can reduce the seismic response of the structure by increasing the damping and dissipating the vibration energy of structures.It has a wide application prospect in actual structural vibration control because of simple device and economical material.In view of the poor seismic behaviors of assembled frame structure connections,various energy dissipation devices are proposed to improve the seismic performance.The finite element numerical analysis method is adopted to analyze relevant energy dissipation structural parameters.The response spectrum of a 7-story assembled frame structure combined the ordinary steel support,ordinary viscoelastic damper,and viscoelastic damper with displacement amplification device is analyzed.The analysis results show that the mechanical behavior of assembled frame structure with ordinary steel supports are not significantly different from those without energy dissipation devices.The assembled frame structure with viscoelastic damper has better seismic performance and energy dissipation,especially for the viscoelastic damper with displacement amplification devices.The maximum value of inter-story displacement angle decreases by 32.24%;the maximum floor displacement decreases by 31.91%,and the base shear decreases by 13.62%compared with the assembled frame structures without energy dissipation devices.The results show that the seismic fortification ability of the structure is significantly improved,and the overall structure is more uniformly stressed.The damping structure with viscoelastic damper mainly reduces the dynamic response of the structure by increasing the damping coefficient,rather than by changing the natural vibration period of the structure.This paper provides an effective theoretical basis and reference for improving the energy dissipation system and the seismic performance of assembled frame structures.
文摘Pilot contamination limits the performance of massive multiple-input multiple-output（MIMO） system severely due to the degraded channel estimation. An efficient way to solve this problem in time division duplex（TDD） wireless system is shifting the location of pilots in time frames used in neighboring cells. However, the shifted frame structure has only been studied in MIMO system with the ideal independent and identically distributed（i.i.d.） channel coefficients. In this paper, the shifted frame structure is studied in a measured channel with a large number of antennas for a certain class of channel fading statistics. To deal with the high inter-cell interference caused by the shifted frame structure in such a measured channel condition, we propose a scenario with a covariance-aided channel estimator. This scenario shows that pilot contamination can be solved and the high inter-cell interference can be made to vanish asymptotically with the number of antennas. The key of the interference rejection is obtaining the precise condition on the second order statistics for the desired and interference signals. The most significant information of the second order statistics comes from two parts, one is the channel state information（CSI） among the base stations（BSs）, the other comes from the estimated information exchanged by the BSs, which depicts the channel between the BSs and the users. The simulations give powerful results of the interference rejection and the achievable rate promotion.
基金supported by National Science Foundation of China under Grant No.61401205
文摘Frame detection is important in burst communication systems for its contribu- tions in frame synchronization. It locates the information bits in the received data stream at receivers. To realize frame detection in the presence of additive white Gaussian noise （AWGN） and frequency offset, a constant false alarm rate （CFAR） detector is proposed through exploitation of cyclic autocorrelation feature implied in the preamble. The frame detection can be achieved prior to bit timing recovery. The threshold setting is independent of the signal level and noise level by utilizing CFAR method. Mathematical expressions is derived in AWGN channel by considering the probability of false alarm and probability of detection, separately. Given the probability of false alarm, the mathematical relationship between the frame detection performance and EJNo of received signals is established. Ex- perimental results are also presented in accor- dance with analysis.
文摘The new variational principle of Gauss's form of nonlinear nonholonomic nonpotential system relative to non-inertial reference frame is established by constructing generalized inertial potentials. Naether's theorem and Naether's inverse theorem of the system above is presented and proved. Finally, one example is given to illustrate the application.
基金Supported by the Natural Science Foundation of China under Grant Nos. 90921010,and 11174373the Fundamental Research Program of China under Grant No. 2010CB923104the Fundamental Research Funds for the Central Universities under Grant Nos. SWJTU09CX078 and 2010XS47
文摘We investigate the dynamics of measurement-induced disturbance(MID) for a qubit-qutrit system in noninertial frames under various multi-local decoherence channels(i.e.,dephasing,phase-flip,bit-(trit-) flip,bit-(trit-) phase-flip,and depolarizing channels).We find that,for any acceleration,the MID can decay in a monotonic way to zero or to a nonzero steady value(i.e.,residual MID exists).Consequently,no sudden death of the MID occurs,which is different from entanglement.
文摘This paper presents the generalized principles of least action of variable mass nonholonomic nonconservative system in noninertial reference frame, proves the equivalence between Holder form and Suslov form, and then obtains differential equations of motion of variable mass nonholonomic nonconservative system in noninertial reference frame.
文摘A double system of exponents with piecewise continuous complex-valued coefficients are considered. Under definite conditions on the coefficients the frame property of this system in Lebesgue spaces of functions is investigated. Such systems arise in the spectral problems for discontinuous differential operators.
基金supported by the Youth Foundation of Jilin University
文摘The prevention of common pig diseases depends on the experience of veterinarian greatly due to complexity of piggery pestilence. The expert system for the prophylaxis and treatment of common pig diseases is able to make the complex task more effective. The construction and im- plementation of this expert system is based on the bottleneck problems of the traditional expert system knowledge acquisition and the frame descrip- tion of symptoms of common pig diseases, used the knowledge project method and technology, and combined the uncertainty inference and dispel- ling strategy of matching conflict and technology of multimedia. This expert system is used to imitate expert thinking and supplement or substitute for veterinary experts to guide the prophylaxis and treatment of common pig diseases. The overall structure, knowledge expression, inference mecha- nism and system realization would be expounded emphatically.
文摘Papain was used to hydrolyse fish frames under controlled conditions at a batch-pilot plant scale- process, for the production of fish protein hydrolysates (FPH). Mass balance calculations were carried out so that the rate of hydrolysis, rate of protein solubilisation and yields could be estimated. Almost complete hydrolysis could be achieved in 1 hour, at 40oC, with no pH adjustment, at 0.5% (5 g.kg-1) enzyme to substrate ratio (E/S, were S is Kjeldahl protein) using whole fish frames (including heads and flaps). This was achieved both with the addition of water (1/1 to 2/1 frames/water) but more importantly from commercial considerations without the initial addition of water (after mincing of the fish material). The degree of protein solubilisation ranged between 71% - 86% w/w. Four different processes are described, namely: 1) a soluble spray-dried FPH powder 2) a liquid FPH 3) a partly soluble, spray dried FPH powder and 4) a crude, drum-dried protein for animal consumption. The amino acid profile of the FPH was identical to that of the parent substrate (fish frames).
文摘This paper puts forward a new drafting system of the rubbed roving frame, which consists of a nine-link gear, two slipping gears. It has brought forward a new design method of the nine-link gear and the slipping gears, and set up approximate formulas for modification coefficients of gears for the first time. And the principles of transmitting rate designing for the system are given. The calculating results demonstrate that the new design method satisfies the demands of processing technology. This mechanism has been used successfully in the kind of rubbed roving frame.
