Chiral (1S)- and (1R)-camphyl α-diimine nickel complexes were synthesized respectively with (1S)-(+) camphorquinone and (1R)-(−) camphorquinone as raw reagents and used as catalyst precursors for olefin polymerizations. It is found that the ligand chirality has no influence on catalytic activity and regioselectivity for olefin polymerizations. Ethylene, propylene, 1-hexene, and 4-methyl-1-pentene polymerizations with the camphyl α-diimine nickel activated by AlEt2Cl can exhibit some living characteristics under the optimized conditions. The resultant polypropylenes and poly(1-hexene)s have significantly narrow molecular weight distributions (PDI < 1.2) in a wide temperature range, even at an elevated temperature of 70 °C. Sustainable period of the linear relationship of M n vs polymerization time depends on temperature for propylene and 1-hexene polymerizations. Additionally, high 1,3-enchainment fraction of 45% is observed even at −60 °C for propylene polymerization using the camphyl α-diimine catalyst due to 2,1-insertion of propylene and chain walking.

All manipulations involving air-and moisture-sensitive compounds were carried out under an atmosphere of dried and purified nitrogen with standard vacuum-line, Schlenk, or glovebox techniques. MaterialsSolvents were purified by standard procedures. 2-Pyridinecarboxaldehyde (99%), 2-benzoylpyridine (98%), 2-bromomesitylene (98%), 2,6-diisopropylaniline (98%), 2,6-dimethylaniline (98%) 2,4,6-trimethylaniline (98%), 4-fluoro-2,6-dimethylaniline (98%) and aniline (98%) were purchased from Aldrich Chemical and used without further purification. Trimethylaluminium (TMA，98%) was purchased from Acros. (DME)NiBr 2 was synthesized by the reaction of 1,2-dimethoxyethane with anhydrous nickel(II) bromide, according to the reported procedures. 6a Methylaluminoxane (MAO) was prepared by partial hydrolysis of trimethylaluminum (TMA) in toluene at 0-60 °C with Al 2 (SO 4 ) 3 ⋅18H 2 O as the water source. The initial [H 2 O]/[Al] in molar ratio was 1.3. Polymerization-grade ethylene and extra-pure-grade nitrogen (99.999%)were further purified before feeding into the reactor by passing them through a DC-IB gas purification instrument. Ligands L1 and L6, and the corresponding nickel complexes 1 and 6 were synthesized by our reported methord. 14 Other commercially available reagents were purchased and used without purification. CharacterizationElemental analyses were performed with a Vario EL series elemental analyzer.Mass spectra were obtained using fast atom bombardment (FAB) LCQ DECA XP or

The field-induced soft smart materials are a kind of soft matter whose macroscopic properties (mechanical, or optical) can be significantly and actively controlled and manipulated by external fields such as magnetic field, electric field, temperature or light. In this paper, we briefly review the research and application progress of the field-induced soft smart materials in recent years and discuss the development problems and trend in this research area. In particular, we focus on three typical field-induced soft materials of smart materials: magnetorheological fluid, electrorheological fluid, and temperature and light sensitive polymer gel.

Field practices show the adaptability of the water displacement curve at the ultra-high water-cut stage is poor. The authors first proposed a new water displacement curve, and then put forward a new method to obtain the parameters in the new curve equation. Then a new characterization equation to describe the relationship between water-oil relative permeability ratio and water saturation is proposed, which is the new water displacement curve's theoretical basis. Finally, based on the case study it is proved that the new curve are more accurate in predicting the development performance at the ultra-high water-cut stage.

SUMMARY Compared with surface waves, guided waves are rarely applied in near-surface investigation. The main reason may lie in the complexity of their dispersion curves. Besides, the study and understanding of guided wave dispersion characteristics are now also inadequate and not deep enough. In this paper, we derived the complete theoretical dispersion curves of P–SV-wave and pure P-wave systems in layered media based on the transmission matrix method and obtained the relative displacement amplitude coefficients at the free surface as a function of frequency and phase velocity for both surface and guided waves. By assigning the value of relative displacement amplitude coefficient to the corresponding point (f,v) on dispersion curve, we got a multi-information diagram called relative amplitude dispersion map (RADM). As a unified description of surface and guided waves, RADM not only shows the velocity–frequency relationship but also represents the polarized energy ratio at the free surface by display colours. The accuracy of RADM was proved by synthetic seismic records, in which RADMs fit well with the corresponding dispersion energy of surface and guided waves. In addition, we designed six models with different Poisson's ratio (PR) and different layer numbers for comparison. It shows that the dispersive vertical-to-horizontal amplitude ratio of guided waves is complex and discontinuous in RADM, which brings great difficulty for mode identification and even affects the subsequent inversion. Tests also show that for high PR layers, the trends of guided P–SV-wave dispersion curves are basically consistent with those of pure P wave. With the decrease of PR, dispersion curves of guided P–SV wave gradually deviate from those of pure P wave. However, RADMs can be greatly consistent with the dispersion energy in either case. This is of great significance for the inversion of near-surface P and S velocities by using dispersion relationships of multimode surface and guided waves.

Frequency-domain finite-difference (FDFD) modeling plays an important role in exploration seismology. However, a major disadvantage of FDFD modeling is the computational cost, especially for large-scale models. By compactly distributing nonzero strips, the elongated stencil helps to generate a narrow-bandwidth impedance matrix, improving computational efficiency without sacrificing numerical accuracy. To further improve the accuracy and efficiency of modeling, we have developed an optimal FDFD method with an elongated stencil for 2D acoustic-wave modeling. The Laplacian term is approximated using the directional-derivative method and the average-derivative method. The dispersion analysis indicates that this elongated-stencil-based method (ESM) achieves higher accuracy than other finite-difference methods with the elongated stencil, and it is more suitable for large grid-spacing ratios. To keep the phase-velocity error within 1%, 15-point and 21-point schemes in the ESM only require approximately 2.28 and 2.19 grid points per wavelength, respectively, when the grid-spacing ratio, namely, the ratio of directional sampling intervals, is not less than 1.5. Moreover, we also adopt a variable-stencil-length scheme, in which the stencil length varies with the velocity, to further reduce the computational cost in frequency-domain modeling. Several numerical examples are presented to demonstrate the effectiveness of our ESM.

Seismic anisotropic attenuation and anisotropic velocity exist widely in the earth's interior and have a great influence on the propagation of seismic waves. Ignoring the effects of attenuation anisotropy may lead to amplitude imbalance or noise in reflection seismic imaging, thus reducing the quality of the imaging results. In order to incorporate attenuation anisotropy into imaging methods and explore its effect on imaging, based on a novel two-way pure qP wave equation in viscoacoustic vertical transversely isotropy media, we propose the corresponding reverse time migration and least-squares reverse time migration method. Both imaging methods can accurately obtain subsurface structure information, especially the least-squares reverse time migration has the potential to compute accurate subsurface reflectivity. In this paper, we first introduce the pure qP wave equation in viscoacoustic vertical transversely isotropy media. As the equation is derived from the complex dispersion relation of P wave, wave propagation can be simulated without interference of SV wave and limitation of anisotropic parameters. Then, we derive the corresponding linearized wave equation and adjoint gradient for updating the imaging result. Finally, using two synthetic models, we demonstrate the effectiveness of the imaging method and discuss the effect of attenuation anisotropy on seismic imaging.

The Department of Public Works of Canada initiated in 1968 a joint project with the Department of Energy, Mines and Resources to obtain, mainly by field measurement, information on the wind generated wave climate on the major coastlines and lakes of Canada. The first major year of field measurement was begun in 1970 using Datawell "Waverider" accelerometer buoys and pressure sensors developed by the National Research Council of Canada. The recording units for both sensors have been operated for twenty minutes every three hours; the accelerometer buoys were moored inapproximately 25 fathoms and the pressure sensors located in approximately 30 feet of water. During 1970 accelerometer buoys have been installed and operated on the Pacific coast of Vancouver Island and on the Atlantic coast of Nova Scotia; the pressure sensors were installed and operated on the south coast of Newfoundland. The greatest success was obtained from the accelerometer buoys, however, difficulties were encountered with the mooring system. It is intended that this wave climate study will continue for the next three years, and possibly longer, recording data off the major coastlines and lakes of Canada. Data obtained during the first year of measurement are presented in summarized form in this paper. It is intended that all the data recorded during the project will be presented in this form. INTRODUCTION Canada has a coastline of considerable length and a correspondingly large continental shelf area. Many of its national resources are closely related to the coastal and marine environment. A requirement exists within Canada, and similarly within other maritime countries, for environmental data from the surrounding oceans and internal seas. Wave information forms an integral part of the required data and possibly covers the widest spectrum of requirements. Synoptic information for fishing fleets and ship routing, design wave predictions for coastal protection and harbours, statistical data for oil drilling operations and wave climate forecasts for ferry services form only part of the overall need. It is difficult to imagine any oceanic undertaking that does not require wave data in some aspect of its program. Realizing the need for an observation and analysis program to support the growing expenditure on marine projects the Canadian government approved a proposal initiated by the Department of Public Works undertaking the measurement of the wave climate of Canadian coastal and inshore waters. The following report is an account of the first full year of this program together with the presentation of resultsfrom one of the East Coast locations. HISTORY In 1968 the Department of Public Works initiated a proposal to conduct a wave climate survey of Canadian coastal and inshore waters.