Analytical Planar Mixing Transfer Functions for Two Coupled Spin-1 Nuclei

Analytical coherence transfer functions are presented for spin systems consisting of two spins 1 under planar mixing conditions. Compared to isotropic mixing experiments, larger transfer amplitudes are found and differences in the multiplet patterns are discussed.     

A model for vibration transmission of light-heavy structures

The vibration transmission of light-heavy structures is investigated in this paper. The light-heavy structure consists of a thin beam and a mass block. Based on numerical simulations with the finite element method and experiments, the block's effect on the thin beam is defined. A theoretical model for this beam-block structure is successfully developed, which is validated and agrees very well with the numerical and experimental models. Two kinds of transfer functions of velocities between any two points on the beam-block structure are studied experimentally and theoretically. The theoretical transfer functions agree well with the experimental results. There are peaks and valleys in the transfer functions, where the peaks occur at the anti-resonant frequencies of the second point and the valleys at the anti-resonant frequencies of the first point. Away from these peaks and valleys the magnitude of the transfer functions are about 0 dB for two points on the beam, and about 20 dB in our experiments for a point on the beam and another point on the block (close to the theoretical prediction of 18 dB determined by the mass ratio of the beam and the block). With these transfer functions, new techniques might be developed for indirect measurement of the vibration of the thin beam by measuring the vibration of the block.     

直线变压器驱动源磁芯能量传递效率

 磁芯是直线变压器驱动源(LTD)的关键部件之一,起着初、次级能量传递和次级电压感应叠加的作用,磁芯的能量传递效率对LTD系统的效率、体积和重量影响显著。对LTD系统中影响磁芯能量传递效率的原因进行了初步的分析,并利用Pspice软件的非线性磁芯模型对磁芯的工作过程和损耗进行了模拟计算,最后对LTD磁芯的能量传递效率进行了初步的实验研究,在工作电压为20 kV时、脉宽约220 ns时,在2.8 Ω负载上获得了大于60%的能量传递效率。     

Quantum State Transfer with Tunable Couplings for Superconducting Qubits

Currently, scalability and decoherence are still the two crucial problems for realizing large-scale quantum computation. To transfer information efficiently in the field of quantum computer and quantum communication, we must solve the two problems reasonably. Here, we propose an efficient scheme for the implementation of quantum states transfer in different couplings of superconducting devices, which are coupled weakly over a long distance. It is found that the isotropic Heisenberg coupling can offer the perfect operation for arbitrary states transfer with the shortest time. The scheme is feasible because the couplings have been demonstrated in actual experiments recently.     

New Experimental Data for the Validation of Radiative Heat Transfer

The numerical simulation of radiative heat transfer is now well established. Key ingredients in such a simulation model are calculated view factors that are used to describe the exchange of radiated energy between different surfaces. Several methods for the calculation of these geometrical factors are available, including Integration, Monte Carlo, and the Hemi-cube methods. Several analytical test cases are also available, such as the well-known “parallel plates” case, which allow modelers to validate their view factor routines. However, there is much less information available that combines both view factor information and heat transfer effects simultaneously.

This article describes the construction of a simple testing rig that allows experiments to be performed that combine view factor effects with measured heat transfer exchanged between surfaces only. The equipment has been used to consider simple cases, such as the parallel plates test case, and also cases where shadowing is important. The results of these experiments are presented as experimental benchmarking data for model users and developers.     

直线变压器驱动源磁芯能量传递效率

磁芯是直线变压器驱动源(LTD)的关键部件之一,起着初、次级能量传递和次级电压感应叠加的作用,磁芯的能量传递效率对LTD系统的效率、体积和重量影响显著。对LTD系统中影响磁芯能量传递效率的原因进行了初步的分析,并利用Pspice软件的非线性磁芯模型对磁芯的工作过程和损耗进行了模拟计算,最后对LTD磁芯的能量传递效率进行了初步的实验研究,在工作电压为20 kV时、脉宽约220 ns时,在2.8 Ω负载上获得了大于60%的能量传递效率。     

An Arctic-Type Shallow-Water Acoustic Waveguide as an Information Transmission Channel for Underwater Communications

Acoustical Physics - Model experiments are used to obtain the transfer functions of an Arctic-type shallow-water acoustic waveguide in the spring–summer period, including in the presence of...     

NMR magnetization transfer as a tool for characterization of nanoporous materials

The application of nuclear magnetic resonance magnetization transfer experiments to probe the surface-to-volume ratio and pore morphology of porous materials with characteristic pore sizes of 1-100 nm is described. The method is based on the phenomenon of incomplete freezing of liquids in small pores where a few monolayers adjacent to the pore walls remain liquid. Sufficient difference between the transverse relaxation times in the solid frozen core and liquid surface layer allows the initial preparation and subsequent re-equilibration of a solid-liquid magnetization grating. The method is demonstrated using model nanoporous materials with known characteristics. The ensuing problems of the mechanism of the magnetization transfer through the interface and within the frozen core are discussed and elucidated by pulsed-field-gradient NMR experiments.     

Dissection of heteronuclear NMR experiments for studies of magnetization transfer efficiencies

Modern NMR experiments for applications with biological macromolecules in solution typically include multiple magnetization transfer steps. When working with large structures, a significant fraction of the magnetization is lost during these transfers. For the design and optimization of complex experimental schemes, the magnetization transfer efficiencies have therefore commonly been calculated from the spin relaxation times. This paper now suggests a new method for measurement of individual transfer efficiencies directly with the system of interest, using short, reliable experiments. Initial applications of this approach with a 110,000 Da protein indicate that there is a wide range of transfer efficiencies among individual spin pairs in a structure of this size, which leads to a correspondingly large variation of the individual signal intensities and the need for techniques to enhance the weak signals.     

Failures in the discrete models for flow duct with perforations: an experimental investigation

Acoustical experiments have been performed at low frequencies on perforated tubes with a back cavity by means of the “2 sources method” and are compared to classical models. The four elements of the transfer matrix of the device are measured with flow. The classical lumped model relates the sound pressure and the axial velocity on both sides of the lined region. Since this model fails, a new empirical model has been proposed to take into account the experimental data. The new transfer matrix of the measured device is calculated and the results fit surprisingly well with the experiments. It is therefore possible to make a segmentation model of the aeroacoustical behaviour of a perforated tube with a partitioned chamber.     

Experimental study of heat transfer processes for macroparticles in a dusty plasma

The results of the experimental study of heat transfer processes in liquid dusty structures are reported. The experiments have been carried out for aluminum oxide particles in an rf discharge plasma. The thermal conductivity and thermal diffusivity of the dusty plasma component have been determined by analyzing the steady and unsteady heat transfer processes. The temperature dependence has been obtained for these quantities, which is in qualitative agreement with numerical simulation results for a simple one-atomic fluid.     

Scaling laws for all Liapunov exponents: Models and measurements

We introduce simple diamond models of random symplectic matrices in order to study the scaling laws of all Liapunov exponents. These universal properties appear in physical problems that are modeled by transfer matrices: dynamical systems, random potentials, random fields, etc. Numerical experiments for the general case are in agreement with the results derived from the models.     

Sensitivity of two-dimensional NMR experiments for studying chemical exchange

The conditions required to optimize the sensitivity of two-dimensional experiments for the study of chemical exchange are discussed in detail and compared with results for selective saturation transfer experiments. Details of phase-cycling procedures are also given and a new method of data handling to produce pure absorption lineshapes is presented. The inherent sensitivity of two-dimensional spectra is compared with ordinary NMR spectra with particular regard to the significance of using discrete Fourier transforms. In conclusion, the superior sensitivity of two-dimensional methods over that of conventional techniques is demonstrated for the study of exchange processes in complex molecules.     

The CLIP/CLAP-HSQC: pure absorptive spectra for the measurement of one-bond couplings

Heteronuclear residual dipolar one-bond couplings of organic molecules at natural abundance are most easily measured using t2 coupled HSQC spectra. However, inevitably mismatched transfer delays result in phase distortions due to residual dispersive antiphase coherences in such experiments. In this article, slightly modified t2 coupled HSQC experiments with clean inphase (CLIP) multiplets are introduced which also reduce the intensities of undesired long-range cross peaks. With the corresponding antiphase (CLAP) experiment, situations where alpha and beta components overlap can be resolved for all multiplicities in an IPAP manner. A comparison of the experiments using hard pulses and shaped broadband excitation and inversion pulses on the heteronucleus is given and potential spectral artefacts are discussed in detail.     

Orbit determination for geostationary satellites with the combination of transfer ranging and pseudorange data

Geostationary satellites(GEOs) play a significant role in the regional satellite navigation system.Simulation experiments show that the clock corrections could be mitigated through a single strategy or double differencing strategies for a navigation constellation,but for the mode of individual GEO orbit determination,high precision orbit and clock correction could not be obtained in the orbit determination based on the pseudorange data.A new GEO combined precise orbit determination(POD) strategy is studied in this paper,which combines pseudorange data and C-band transfer ranging data.This strategy overcomes the deficiency of C-band transfer ranging caused by limited stations and tracking time available.With the combination of transfer ranging and pseudorange data,clock corrections between the GEO and the stations can be estimated simultaneously along with orbital parameters,maintaining self-consistency between the satellite ephemeris and clock correction parameters.The error covariance analysis is conducted to illuminate the contributions from the transfer ranging data and the psudoranging data.Using data collected for a Chinese GEO satellite with 3 C-band transfer ranging stations and 4 L-band pseudorange tracking stations,POD experiments indicate that a meter-level accuracy is achievable.The root-mean-square(RMS) of the post-fit C-band ranging data is about 0.203 m,and the RMS of the post-fit pseudorange is 0.408 m.Radial component errors of the POD experiments are independently evaluated with the satellite laser ranging(SLR) data from a station in Beijing,with the residual RMS of 0.076 m.The SLR evaluation also suggests that for 2-h orbital predication,the predicted radial error is about 0.404 m,and the clock correction error is about 1.38 ns.Even for the combination of one C-band transfer ranging station and 4 pseudorange stations,POD is able to achieve a reasonable accuracy with the radial error of 0.280 m and the 2-h predicted radial error of 0.888 m.Clock synchronization between the GEO and tracking stations is achieved with an estimated accuracy of about 1.55 ns,meeting the navigation service requirements.     

Signatures of short-range many-body effects in the dielectric function of silicon for finite momentum transfer

We present an investigation of the dynamic structure factor and of the dielectric function epsilonM(Q,omega) of the prototypical semiconductor silicon for finite momentum transfer, combining inelastic x-ray scattering experiments and ab initio calculations. In contrast with optical spectra, for finite momentum transfer time-dependent density-functional theory in the adiabatic local-density approximation together with lifetime broadening describes the physics of valence excitations correctly. Major structures in the spectra, governed by short-range crystal and exchange-correlation local-field effects, are strongly influenced by a mixing of transitions of positive and negative energies, in striking difference to spectra for vanishing momentum transfer. This mixing gives rise to a pronounced Fano asymmetry.     

Evaluation and optimization of coherence transfer in high molecular weight systems

For very large proteins in the highest magnetic fields, the large chemical shift anisotropy (CSA) of carbonyl carbon deteriorates coherence transfer efficiency in experiments designed for unambiguous sequential backbone assignment. In this communication, coherence throughput of several TROSY experiments is evaluated. Two new experiments, MP-HNCA and HN(CO)CANH, are also introduced as attractive alternatives for sequential assignment purposes of large proteins with correlation time over 50 ns. Their theoretical coherence transfer efficiencies for the interresidual (13)C(alpha) correlations are significantly better than in recently introduced MP-CT-HNCA and sequential HNCA experiments. The improvement with the new experiments is observed already on 60.8 kDa homodimer of protein Cel6A at 800 (1)H MHz.