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Due to the low bonding strength between diamond and copper, the thermal conductivity and mechanical strength of diamond/copper composites are affected. In order to improve the interface bonding strength, this paper prepared diamond/Cu composites with titanium element in two forms: adding titanium to the copper matrix and using titanium coated diamond particles, respectively. The microstructure and composition analysis of the materials were carried out through SEM, EDS, AFM, etc. The bending strength and thermal conductivity of titanium coated diamond/copper composites reached 230 MPa and 480 W/(m·K), respectively, which were higher than the bending strength and thermal conductivity of diamond/Cu composites with added titanium in the matrix (208 MPa and 127 W/(m·K) and significantly higher than the corresponding properties of pure diamond/Cu composites (69 MPa and 108 W/(m·K)). Pre coating a layer of titanium carbide on the surface of diamond can serve as a connecting bridge, effectively reducing interfacial thermal resistance and improving mechanical properties, which is more effective than adding titanium powder to the matrix to improve the bending strength and thermal conductivity of diamond/Cu composites.

Barocaloric effect, previously reported in solid-solid phase transition materials, offers a green alternative to current cooling technology. Here the authors report colossal BCE in n-alkanes associated with liquid–solid transition.

In the era of the digital economy, for platform-based actors making a transition from one business field harmful for the sustainable development of society to a new field, their efficiency in value realization (EVR) has become inseparable from the digital platform used. The relationship between EVR on a platform and business transitions is a topic that has not been fully discussed, especially from the perspective of the platform service system. Also, few studies have explored transaction costs and opportunity costs using queuing theory. To fill these gaps and to inform transitions to sustainability, this paper applied a system dynamics method and proposed a framework for analyzing the relationship between EVR and the transition ratio. Findings suggest that improvements in the EVR lead to decreases in response time and may lead to an improved transition ratio. The ratio between EVR and the “entry rate” is important for predicting the transition ratio. However, preference, platform maturity, and the feedback of the transition ratio cause the effect of EVR to dynamically change. Based on this mechanism, the government can take incentive measures to maintain an acceptable transition ratio. For the power industry, the case simulated for this study, the transition can be improved by effectively transmitting a phasing-out policy for platforms and actors, and by guiding power exchange platforms to set reasonable rules, service levels, and growth rates.

In order to study the effect of negative valve overlap on combustion and emission characteristics of a homogeneous charge compression ignition engine fueled with natural gas and hydrogen, the test and the simulation were conducted using an engine cycle model coupling the chemical kinetic reaction mechanism under different valve timing conditions. Results show that the internal EGR formed by using negative valve overlap could heat the inlet mixtures and improve the spontaneous ignition characteristic of the engine. The residual exhaust gas could slow down the heat release rate, decrease the pressure rise rate and the maximum combustion temperature, and reduce the NOx emission simultaneously. Among the three NVO schemes, the strategy of changing the intake valve opening timing individually can create the least power loss, and the symmetric NVO strategy which changes both the exhaust valve closing timing and the intake valve opening timing simultaneously can achieve the best heating effect of inlet mixtures and the satisfactory decrease of combustion temperature, as well as the largest reduction of NOx emission.

The maturity and affordability of light detection and ranging (LiDAR) sensors have made possible the quick acquisition of 3D point cloud data to monitor phenotypic traits of vegetation canopies. However, while the majority of studies focused on the retrieval of macro scale parameters of vegetation, there are few studies addressing the reconstruction of explicit 3D structures from terrestrial LiDAR data and the retrieval of fine scale parameters from such structures. A challenging problem that arises from the latter studies is the need for a large amount of data to represent the various components in the actual canopy, which can be time consuming and resource intensive for processing and for further applications. In this study, we present a pipeline to reconstruct the 3D maize structures composed of triangle primitives based on multi-view terrestrial LiDAR measurements. We then study the sensitivity of the details with which the canopy architecture was represented for the computation of leaf angle distribution (LAD), leaf area index (LAI), gap fraction, and directional reflectance factors (DRF). Based on point clouds of a maize field in three stages of growth, we reconstructed the reference structures, which have the maximum number of triangles. To get a compromise between the details of the structure and accuracy reserved for later applications, we carried out a simplified process to have multiple configurations of details based on the decimation rate and the Hausdorff distance. Results show that LAD is not highly sensitive to the details of the structure (or the number of triangles). However, LAI, gap fraction, and DRF are more sensitive, and require a relatively high number of triangles. A choice of 100−500 triangles per leaf while maintaining the overall shapes of the leaves and a low Hausdorff distance is suggested as a good compromise to represent the canopy and give an overall accuracy of 98% for the computation of the various parameters.

In this paper, the aperture synthesis processing techniques for the distributed shipborne high frequency hybrid sky-surface wave radar (HFHSSWR) are proposed to improve the azimuth resolution and obtain the velocity vector and the azimuth estimation of the moving target. First, the system geometry and the signal model of the moving target for the distributed shipborne HFHSSWR are formulated, and then the azimuth resolution improvement principle is derived. Second, based on the developed signal model, we propose an azimuth resolution improvement algorithm, which can obtain the synthetic azimuth bandwidth and an improved resolution using sub-band combination. Finally, a target parameters inversion method is introduced to estimate the target velocity vector and the target azimuth, by solving the equations regarding the target geometry and echo signal parameters numerically. The simulations are performed to verify the proposed algorithms. The results indicate that the distributed synthetic aperture techniques effectively improve the azimuth resolution of this radar, and can obtain the target velocity vector and the high-precision estimation of the target azimuth.

Hylogger core scanning system is used to detailed scan shale gas drilling cores, obtaining visible-near infrared (spectral range 380nm-1100nm),short-wave infrared (spectral range 1100nm-2500nm) spectral curves and high-definition core images. Taking Well weican 1 in the West Taikang Uplift in the South China North Basin as an example, based on the analysis of clay mineral types in the core of the target layer, it is judged to be an alkaline deposit environment rich in iron and magnesium with a temperature of about130°C. Combined with mineral information and core image, the core of the target layer is divided,mud shale is developed, the cumulative thickness exceeds 400m, the maximum single layer thickness reaches 38m, at the same time, the hydrocarbon absorption characteristics of the shale section are obvious, it shows a good prospect for shale gas in the region.

Negative thermal expansion (NTE) and magnetic properties were investigated for antiperovskite Ga1−xCrxN0.83Mn3 compounds. As x increases, the temperature span (ΔT) of NTE related with Γ5g antiferromagnetic (AFM) order is expanded and shifted to lower temperatures. At x = 0.1, NTE happens between 256 and 318 K (ΔT = 62 K) with an average linear coefficient of thermal expansion, αL = −46 ppm/K. The ΔT is expanded to 81 K (151–232 K) in x = 0.2 with αL = −22.6 ppm/K. Finally, NTE is no longer visible for x ≥ 0.3. Ferromagnetic order is introduced by Cr doping and continuously strengthened with increasing x, which may impede the AFM ordering and thus account for the broadening of NTE temperature window. Moreover, our specific heat measurement suggests the electronic density of states at the Fermi level is enhanced upon Cr doping, which favors the FM order rather than the AFM one.

The adsorption isotherms and structural evolution of alkyl quaternary ammonium bromide (Cn TAB) on graphite oxide (GO) were measured by means of an elemental analyzer, X-ray diffraction and Fourier transform infrared spectroscopy. In order to interpret the adsorption mechanism of surfactants onto GO, the adsorption kinetics and thermodynamics were further investigated. It was found that GO is a relatively efficient adsorbent within a wide range of temperatures (297–353 K), and the Cn TAB was intercalated and then agglomerated into the interlayer spacing of GO via ionic bonding and hydrophobic bonding. The saturation amount of alkyl ammonium adsorbed on GO was decreased with the rise in temperature, and the experimental data fitted well into the modified Langmuir (Langmuir-Freundlich) equation. In addition, the negative values of ΔG and ΔH showed that the adsorption process of Cn TAB onto the GO was spontaneous and exothermic.

The effect of fatigue on ZrCuAl amorphous metals induced by mechanical cyclic loading is investigated using inelastic neutron scattering and the pair density function analysis of neutron diffraction data. With cooling, the local atomic structure undergoes reorganization under fatigue that is directly related to the number of fatigue cycles. Also under fatigue, suppression in the atomic dynamics is observed as well. A structural restructuring occurs within a 4 Å radius and intensifies with increasing the compression cycles, whereas the vibrational density of states is attenuated as the intensity shifts towards the elastic, zero-energy transfer peak. The combined static and dynamic structural effects are a signature of the microscopic changes brought about by fatigue, and together may be the onset for subsequent behaviors following extended cyclic loading such as fracture. Even after the load is removed, the structural changes described here remain and increase with repeated cyclic loading which is an indication that the lattice deforms even before shear bands are formed.

The shipborne High-Frequency Hybrid Sky-Surface Wave Radar integrates a sky-wave transmitting channel and a ground-wave receiving channel on a shipborne platform. This hybrid radar system combines a skywave source with the added flexibility of a far-away shipborne radar. Ionospheric stratification and height uncertainty introduce uncertainties in the sky-wave channel, resulting in multiple measurements of one target. Additionally, the shipborne platform position is affected by sea state, causing errors in azimuth accuracy setting and subsequently reducing target tracking precision. In this paper, we propose for the first time a target tracking method that combines ionospheric variations with the motion of a shipborne platform. It introduces the variational Bayesian method into the multiple detection mode, which solves the effects of ionospheric altitude error and orientation error of shipborne platforms due to different sea states on target tracking. Simulation experiments validate the effectiveness of the proposed method. Therefore, the proposed method promises advancements in shipborne radar systems for maritime surveillance applications. [ABSTRACT FROM AUTHOR]