Single-Shot Measurement of Transient Phase Shift Induced by Laser Wake

Based on the frequency-to-time mapping relation of the linearly chirped pulse, the temporal phase shift induced by a laser-excited wake in a helium gas jet is measured using a chirped-pulse spectral interferometry with ～ 140 fs resolution over a temporal region of I ps in a single shot. In this measurement, the image of the wake is obtained with one-dimensional spatial resolution and temporal resolution limited only by the bandwidth and chirp of the pulse. The ＇bubbles＇ feature of the wake structure, along with multiple wakes excited by the main lobe and the side lobe of a laser focal-spot, is captured simultaneously.

Sparse Approximation of Data-Driven Polynomial Chaos Expansions: An Induced Sampling Approach

One of the open problems in the field of forward uncertainty quantification(UQ)is the ability to form accurate assessments of uncertainty having only incomplete information about the distribution of random inputs.Another challenge is to efficiently make use of limited training data for UQ predictions of complex engineering problems,particularly with high dimensional random parameters.We address these challenges by combining data-driven polynomial chaos expansions with a recently developed preconditioned sparse approximation approach for UQ problems.The first task in this two-step process is to employ the procedure developed in[1]to construct an"arbitrary"polynomial chaos expansion basis using a finite number of statistical moments of the random inputs.The second step is a novel procedure to effect sparse approximation via l1 minimization in order to quantify the forward uncertainty.To enhance the performance of the preconditioned l1 minimization problem,we sample from the so-called induced distribution,instead of using Monte Carlo(MC)sampling from the original,unknown probability measure.We demonstrate on test problems that induced sampling is a competitive and often better choice compared with sampling from asymptotically optimal measures(such as the equilibrium measure)when we have incomplete information about the distribution.We demonstrate the capacity of the proposed induced sampling algorithm via sparse representation with limited data on test functions,and on a Kirchoff plating bending problem with random Young’s modulus.

Application of geophysical-geochemical method in verification of stream sediment anomaly in Baoxinggou area of Heilongjiang

Baoxinggou area is located in northern Daxing'anling. In this area,comprehensive use of geophysical and geochemical exploration methods plays an important role in the prospecting,and has yielded some application results so far. Based on the 1 /100 000 stream sediment anomaly survey,the methods of 1 /20 000 soil geochemical measurement,trenching engineering on the earth's surface and 1 /10 000 IP intermediate gradient survey were all used to verify and decompose drainage anomalies,as well as to find and locate ore bodies. In this way,an effective,economical and quick prospecting method was concluded,which focuses on the middle and lower mountain forest swamp landscape in the northern part of Daxing'anling,and provides reference for the prospecting in the area.

Single-turnover and multiple-turnover measurement of phytoplankton photosynthesis parameters using variable light pulse induced fluorescence

Using a measurement system based on fluorescence induced by variable pulse light, photosynthesis parameters of chlorella pyrenoidosa are obtained, employing single-turnover and multiple-turnover protocols under darkadapted and light-adapted conditions. Under the light-adapted condition,σ’PSII is larger, and F’v/F’m（ST） and F’v/F’m（MT） are smaller than those of the dark-adapted condition, but the corresponding parameters possess good linear correlations.Fm（MT）, F’m（MT）, Fv/Fm（MT） and F’v/F’m（MT） which are measured using the multipleturnover protocol, are larger than those of the single-turnover protocol. The linear correlation coefficient between Fm（ST） and Fm（MT） is 0.984,and Fv/Fm（MT） = 1.18 Fv/Fm（ST） The linear correlation coefficient between F’m（ST） and F’m（MT） is 0.995, and F’v/F’m（MT） = 1.36 F’v/F’m/（ST）.

Quantum Correlations in Heisenberg XY Chain

Quantum correlations measured by quantum discord （QD）, measurement-induced distance （MID）, and geometric measure of quantum discord （GMQD） in two-qubit Heisenberg XY spin chain are investigated. The effects of DM interaction and anisotropic on the three correlations are considered. Characteristics of various correlation measures for the two-qubit states are compared. The increasing Dz increases QD, MID and GMQD monotonously while the increasing anisotropy both increases and decreases QD and GMQD. The three quantum correlations are always existent at very high temperature. MID is always larger than QD, but there is no definite ordering between QD and GMQD. PACS numbers： 03.65.Ta, 03.67.Mn