Numerical Simulation on Jet Formation of Shaped Charge with Different Liner Materials

In this paper, the effect of liner material of the shaped charge on jet formation and its penetration capability is investigated by experimental and numerical methods. Liner materials investigated in this paper are copper, steel, and aluminium, respectively. Pulse X-ray photographic technology to shoot the formation of jet is employed to obtain the tip velocity and the diameter of jet. A two-dimensional multi-material code is designed to simulate the entire process from jet formation to penetrating a target. A markers on cell lines method is utilised to treat the multi-material interface. The results show that aluminium jet has the highest velocity with the poorest penetration capability. Copper jet has the strongest penetration capability with a velocity higher than that of steel jet, but lower than that of aluminium jet. The simulated results agree with the experimental results very well. It also indicates that the code developed can not only address large distortion problems but also track the variation of multi-material interfaces. It is favourable to simulate the explosive loading on thin-wall structure such as shaped charge. It is proved that authors’ method is feasible and reliable for optimising the structure of shaped charge jet to dramatically improve its tip velocity and penetration capability, and provides an important theoretic basis for designing high explosive anti-tank warhead.Defence Science Journal, Vol. 65, No. 4, July 2015, pp. 279-286, DOI: http://dx.doi.org/10.14429/dsj.65.864

Phytoremediation of heavy metal-contaminated sites: Eco-environmental concerns, field studies, sustainability issues and future prospects

Environmental contamination due to heavy metals (HMs) is of serious ecotoxicological concern worldwide because of their increasing use at industries. Due to non-biodegradable and persistent nature, HMs cause serious soil/water pollution and severe health hazards in living beings upon exposure. HMs can be genotoxic, carcinogenic, mutagenic, and teratogenic in nature even at low concentration. They may also act as endocrine disruptors and induce developmental as well as neurological disorders and thus, their removal from our natural environment is crucial for the rehabilitation of contaminated sites. To cope with HM pollution, phytoremediation has emerged as a low-cost and eco-sustainable solution to conventional physico-chemical cleanup methods that require high capital investment and labor alter soil properties and disturb soil microflora. Phytoremediation is a green technology wherein plants and associated microbes are used to remediate HM-contaminated sites to safeguard the environment and protect public health. Hence, in view of the above, the present paper aims to examine the feasibility of phytoremediation as a sustainable remediation technology for the management of metals-contaminated sites. Therefore, this paper provides an in-depth review on both the conventional and novel phytoremediation approaches, evaluate their efficacy to remove toxic metals from our natural environment, explore current scientific progresses, field experiences and sustainability issues and revise world over trends in phytoremediation research for its wider recognition and public acceptance as a sustainable remediation technology for the management of contaminated sites in 21st century

Real-Time Single Frequency Precise Point Positioning Using SBAS Corrections

Real-time single frequency precise point positioning (PPP) is a promising technique for high-precision navigation with sub-meter or even centimeter-level accuracy because of its convenience and low cost. The navigation performance of single frequency PPP heavily depends on the real-time availability and quality of correction products for satellite orbits and satellite clocks. Satellite-based augmentation system (SBAS) provides the correction products in real-time, but they are intended to be used for wide area differential positioning at 1 meter level precision. By imposing the constraints for ionosphere error, we have developed a real-time single frequency PPP method by sufficiently utilizing SBAS correction products. The proposed PPP method are tested with static and kinematic data, respectively. The static experimental results show that the position accuracy of the proposed PPP method can reach decimeter level, and achieve an improvement of at least 30% when compared with the traditional SBAS method. The positioning convergence of the proposed PPP method can be achieved in 636 epochs at most in static mode. In the kinematic experiment, the position accuracy of the proposed PPP method can be improved by at least 20 cm relative to the SBAS method. Furthermore, it has revealed that the proposed PPP method can achieve decimeter level convergence within 500 s in the kinematic mode

Does Marketization Promote High-Quality Agricultural Development in China?

Over the past 40 years of reform and opening, the enhancement in marketization has greatly promoted the development of the Chinese economy. At present, China’s economic development model has shifted from a focus on speed to a focus on quality. Against this background, it is necessary to further promote marketization reform to promote high-quality development in China. This paper begins with an introduction to high-quality agricultural development and the degree of marketization. According to the definitions of high-quality development and marketization, we constructed an index of high-quality agricultural development and an index of marketization degree, respectively. First, we determined the characteristics of high-quality agricultural development in China. There are large regional differences in agriculture development, but these disparities are improving simultaneously, and regional differences are showing a narrowing trend, except for the western region. Then, we measured the impact of marketization reforms on high-quality agricultural development using the Quadratic Assignment Procedure. Based on sample data from 2009 to 2019, this paper found that marketization reform has played a significant role in promoting high-quality agricultural development. The three sub-indicators of non-state-owned economy, factor market, and the market’s level of order, which represent the marketization degree, had significant impacts on reducing regional differences in high-quality agricultural development. Additionally, the effects of these three variables gradually increased, narrowing the regional differences in high-quality agricultural development. Finally, we suggested that promoting the development of a non-state-owned economy, factor market, and the market’s level of order would be an important path to boosting the high-quality development of agriculture

<span style="mso-fareast-font-family:SimHei" lang="EN-US">Influence of MoO₄^2- <span style="mso-fareast-font-family:SimHei" lang="EN-US">on crystalline perfection and optical properties of potassium dihydrogen phosphate (KDP) crystal </span></span>

105-110A series of KDP crystals are grown by rapid growth method by altering the concentrations of the MoO42- in the range from 0 to 500 ppm (mol ratio). The growth habits of the KDP crystals suggest that MoO42- possess the similar effect with metallic cations, which can inhibit the growth of prismatic faces of KDP crystal. Lower concentrations of MoO42- could induce liquid inclusions in the prismatic sector. The liquid inclusions overlapped with each other. However, higher concentrations of MoO42- can cause detached rod-like liquid inclusions in the pyramidal sector. With a rise of MoO42- concentration, the static extinction ratio of KDP crystals decreased, and the full width at half maximum of the rocking curves is broadened. MoO42- enhanced the transmittance in the range of 200-400 nm for prismatic sector, which is attributed to that MoO42- is prone to be absorbed onto (100) face, and consequently blocked and the entrance probability of metallic cations into KDP crystal. The conoscopic interference indicates the optical homogeneity of KDP crystal is spoiled by MoO42-. Additionally, MoO42- can increase the density of light scatters and the size of single light scatter

Polarization-Dependent Optoelectronic Performances in Hybrid Halide Perovskite MAPbX₃ (X = Br, Cl) Single-Crystal Photodetectors

Hybrid organic–inorganic lead halide perovskites (HOIPs) have received significant attention because of their impressive performances in the fields of solar cells and photoelectric detection. In the past five years, great efforts have been made to improve the crystallinity, reduce grain boundaries, and enhance the stabilities of perovskite films. Compared with films, HOIP single crystals possess fewer grain boundaries and stronger optoelectronic properties and can be applied in optoelectronic devices. As the most popular HOIP member, single crystals of MAPbX₃ (X = Br, Cl) are deemed as important candidates for ultraviolet–visible photodetectors, in which the crystal structure anisotropy largely affects the detection performance. In this study, high-quality cubic single crystals of MAPbBr₃ and MAPbCl₃ were successfully grown from solutions. Taking advantages of their smooth (100) facets, planar metal–semiconductor–metal photodetectors were fabricated using Au interdigitated electrodes. The optoelectronic performances under nonpolarized and linearly polarized lights were explored. The optoelectronic performances were dependent on linearly polarized lights. Interestingly, both responsivity and external quantum efficiency were greatly enhanced under the excitation with linearly polarized lights. Moreover, the polarization-related optical absorptions and the electron densities within the (100) plane could be used to interpret different optoelectronic performances of single crystals of MAPbX₃ (X = Br, Cl) under various linearly polarized lights

Enhanced Optoelectronic Performance on the (110) Lattice Plane of an MAPbBr₃ Single Crystal

Hybrid organic–inorganic lead halide perovskites have attracted significant attention due to their impressive optoelectronic properties. MAPbX₃ (MA= CH₃NH₃⁺, X= Cl, Br or I), the most popular member of this family, has been recognized as an important next-generation optoelectronic materials contender, and remarkable progress has been achieved in both thin films and single crystals. However, the lack of optimizations in energy harvest, transportation, carrier extraction, and process compatibility is hindering their future development. In this study, a triangle prism MAPbBr₃ single crystal exposing (100) and (110) crystallographic planes was successfully synthesized, and the optoelectronic performances of these two lattice planes were systematically explored by employing a planar metal–semiconductor–metal (MSM) device. Compared to the device fabricated on the (100) plane, a 153.33% enhancement of responsivity was achieved under 10 μW irradiation and 10 V bias on the (110) plane. Finally, possible mechanism for such an enhancement was discussed based on the different defect migration behaviors of (100) and (110) planes

Design Growth of MAPbI₃ Single Crystal with (220) Facets Exposed and Its Superior Optoelectronic Properties

MAPbI₃ is deemed as the most prominent member in hybrid perovskites family because of its extremely optoelectronic properties. However, some issues and puzzles are still in expectation of their answers, such as stabilities, hysteresis, ferroelectricity, and so on. To bridge the distinctions between MAPbI₃ single crystal and thin films, large-size single crystals are demanded. On the contrary, crystal structure anisotropy-dependent optoelectronic properties is an inevitable topic. A series of large-size MAPbI₃ single crystals with (220) facets exposed were successfully grown, using high concentration solutions and large-size seed crystals to match growth rates of (100) and (220) facets. The optoelectronic properties of photocurrents, responsivity, EQE, and detectivity clearly showed significant anisotropy of optoelectronic properties in MAPbI₃ single crystal. According to ion migration theory, the anisotropy of optoelectronic properties was interpreted. We hope this result will be helpful to guide oriented growth MAPbI₃ thin films