bluuebunny/crossref_metadata_2025 huggingface dataset:
The Progress of Offshore CO2 Capture and Storage
Authors: Liu Peilin , Wang Xueyuan , Chen Wenfeng , Hu Rong , Li Xiaohan
Published: December 2021

With the development of the offshore oil and gas fields, more and more offshore oil and gas fields are found to have high carbon dioxide. In addition, as peaking carbon dioxide emissions and carbon neutrality were written into the government work report for the first time, the correct separation and emission of CO2 have become a key issue that needs to be solved by offshore oil and gas fields. In this paper, we studied two CO2 separation methods suitable for offshore platforms and the current status of CO2 offshore storage and application. Moreover, the development of offshore carbon dioxide storage application was investigated in detail, and the technical characteristics and application prospects of CO2-EOR and CO2 replacing combustible ice were analysed and discussed. This paper analyses the challenges and countermeasures of offshore CO2 storage from many aspects. It provides a theoretical reference for future CO2 treatment in offshore oil and gas fields.
Application of well-seismic reservoir prediction technology in oilfield
Authors: Zhang Xiaona
Published: December 2021

This study mainly takes the thick oil layer in Lamadian Oilfield as an example. This oil layer is mainly developed in the area dominated by fluvial sediments, and the reservoir sand body space changes frequently. If we only rely on the traditional single well logging data, it is difficult to directly and effectively predict the changes of the whole sedimentary sand body, and the spatial configuration relationship between river boundary and other sedimentary microfacies can not be effectively predicted. In order to effectively improve the understanding of cross-well sand bodies, it is necessary to effectively combine well seismic with reservoir prediction technology, give full play to the advantage of high resolution of well seismic in the longitudinal direction, and predict its specific adaptability and application according to different situations, so as to better improve the prediction accuracy of reservoir sand bodies and provide important information data for the rational adjustment of cross-well encryption and the formulation of effective measures to tap potential. Based on this, this article deeply analyzes the application value of well-seismic combined reservoir prediction technology in oil fields.
Research and Analysis of Perforating Cable Fishing Technology
Authors: Qu Liping
Published: December 2021

Perforation gun and cable are stuck underground, which often occurs in cable perforation. Whether the perforation cable gets stuck properly or not will not only affect the cost of accident treatment, sometimes even affect the success or failure of a well, and sometimes delay the best time of other well layout; Therefore, the unblocking and fishing technology of perforating gun is an important part of perforating operation. The fishing operation of perforating gun sticking can be divided into two categories: one is the fishing of cable, the other is the fishing of perforating gun body. The shape of fish falls into rope and tube. The stuck fishing work must accurately grasp: well condition data, fish falling situation, fishing tool combination, fish head situation, etc. Combined with the process of accident treatment, this paper studies and analyzes the fishing technology of perforating cable and perforating gun.
key influencing factors and adjustment countermeasures of recovery in heavy oil reservoir of water flooding
Authors: Wei Qingting , Zhen Guinan , Wang Weilong , Qin Jiamin , Luo Hongcheng , Zhao Xuejie , Xue Rui , Wu Xinbo
Published: December 2021

The recovery ratio is an important indicator to evaluate the effectiveness and performance of oilfield development. In order to clarify the key factors of oilfield recovery ratio in the stage of super-high water cut, 9 dynamic indicators of 12 blocks are analyzed in heavy oil reservoir of eastern China in application of reservoir engineering principles and statistical analysis methods. The results show that the four key factors of recovery are the well density, the ratio of producing wells and injecting wells, net cumulative injecting rate and the bottom hole flow pressure, and the weight of each indicator is quantified. In the horizontal contrast, comprehensive forecasting target recovery is compared with the current recovery by the dynamic method to determine according to typical block BXD. Four of important factors are discussed for the previous trend and the countermeasures of according adjustment are put forward. The proposed method and the results have a certain reference value of the theoretical research and practical application in the stage of super-high water cut oil-field.
Economic feasibility evaluation of shale gas stratified development in Chongqing area
Authors: Yin Chengxin , Zhou Jun
Published: December 2021

Shale gas as a clean green energy has been rapidly developed in China. At present, the vertical production rate of shale gas in Chongqing area is low, and it is difficult to take into account the whole highquality shale segment with thickness of tens of meters only by one well pattern. In this paper, the internal rate of return (IRR) is used to calculate the impact of different costs and exploitation conditions on the development effect of two shale gas layers. The results show that shale gas development will be profitable only when the cost per well is controlled at around 70 million and production is provided at more than 100 million cubic meters. Domestic producers should further reduce the cost of shale gas development, increase the productivity of single well and maximize the benefit of domestic shale gas development by means of integrated innovation and technological optimization.
Factors affecting chemical heat washing efficiency of oily sludge and Demulsification Mechanism
Authors: Yang Yong , Wang Yijun , Gao Zebin , Zhang Long , Qu Chengtun , Yang Bo
Published: December 2021

Oily sludge belongs to the hazardous waste specified in the national hazardous waste list. It will directly or indirectly threaten the ecological environment and human health. This paper introduces the advantages of chemical hot washing of oily sludge. This paper discusses the main factors affecting the treatment effect, Demulsification Mechanism and research progress in the treatment of oily sludge by chemical thermal washing, and puts forward some suggestions on the future research and development direction of oily sludge utilization and disposal.
Study on the application of natural gas to inland and coastal ships in China
Authors: Li Kun , Li Xiang , Zhang Jianghe
Published: December 2021

In order to promote the green and low-carbon development of ships and promote shipping energy conservation and emission reduction. This paper systematically combed the development of liquefied natural gas (LNG) powered ships in China's inland ships, deeply studied and analyzed the development characteristics of China's new LNG powered ships and reconstructed LNG powered ships, so as to provided reference experience and lay a foundation for China to continue to promote the application of LNG in the water transportation industry in the future.
Analysis of Petroleum Geological Exploration and Reservoir Evaluation Methods
Authors: Guan Xin
Published: December 2021

As one of the important natural resources, oil resources play an irreplaceable role in China's social and economic development. At present, the social demand for oil is increasing gradually, and China's oil production is in the forefront of the world, which is both an opportunity and a challenge for the development of the oil industry. The research on petroleum geological exploration and storage in China is relatively lacking. As a non-renewable resource, excessive exploitation of oil will lead to the shortage of natural resources in China, which is not only extremely unfavorable to the development of the oil industry, but also leads to the collapse of China's social economy. Therefore, the relevant staff must do a good job in the corresponding reservoir work, conduct in-depth research on the exploration technology, and fully implement the reservoir evaluation scheme system, so as to improve the overall comprehensive level of China's petroleum geological exploration, carry out protective development on the utilization of petroleum resources on the basis of meeting the needs of China's social development, and improve the utilization rate of petroleum resources.
A well selection method of CO2 huff and puff in heavy oil reservoir with edge and bottom water based on water cut
Authors: Wang Jia , Liu Tongjing , Shi Hengyu , Diwu Pengxiang , Zhou Jian , Zhao Lekun , Ni Juan , Shi Yan
Published: December 2021

The water cut of heavy oil reservoir with edge and bottom water rises rapidly and the recovery degree of crude oil is low. CO2 huff and puff is an effective measure to improve the recovery of this kind of reservoir, and scientific well selection is the premise of the measure effect. Because the existing well selection methods of CO2 huff and puff in heavy oil reservoir with edge and bottom water mostly take the oil increase of oil well as the evaluation index, ignoring the characterization of well water cut after huff and puff, it is unable to accurately screen all potential wells. Therefore, a quantitative well selection method of CO2 huff and puff in heavy oil reservoir with edge and bottom water based on water cut is proposed. The method is based on fuzzy comprehensive evaluation theory and analytic hierarchy process, and takes the water cut after CO2 huff and puff as the evaluation index. Several groups of typical models are designed to screen the sensitive factors and laws of CO2 huff and puff well selection in heavy oil edge and bottom water reservoir from three aspects of geology, water production law and technology. Than the judgment matrix is established. There is little interference from human factors in the process of well selection, and the rationality of the method has been verified by the effect of field actual well measures. This method is helpful to improve the well selection method system of CO2 huff and puff in this kind of reservoir, and is a reasonable supplement to the existing well selection method which takes the oil increment as the only evaluation index.
Research on intelligent operation and maintenance management technology based on Microgrid group
Authors: Min Wu
Published: December 2021

In this paper, the research and platform development of cloud based microgrid cluster operation and maintenance management technology are carried out in Tibet, the solar thermal power combined microgrid system is built at decentralized load points, the data of each independent new energy system is integrated and shared by using Internet technology, and the unified operation, maintenance, monitoring and management of microgrid cluster are realized through the cloud platform, It can greatly improve the use efficiency of clean energy, improve the power supply quality and reliability of users, reduce the operation and maintenance cost, improve the work efficiency and system operation reliability, realize the intelligent monitoring, operation and maintenance and management of photovoltaic power generation and micro electric network group, and provide new operation and maintenance management methods and development ideas for the multi energy complementary and comprehensive utilization of Tibet Autonomous Region.
Operation analysis of primary and secondary networks of distributed solar heating system in Tibet
Authors: Liu Chengpeng
Published: December 2021

Tibet is located in a high cold and high altitude area. Heating in winter is an important problem to be solved urgently, and the distributed solar heating system provides a solution for the efficient and clean utilization of energy in this area. Through the test and commissioning of the distributed solar heating system with supplementary combustion in Tibet, the operation characteristics of the heating system are analyzed from the temperature changes of the primary network and the secondary network. The research results can provide technical support for the application and promotion of the solar distributed heating system with supplementary combustion in Tibet.
State and prospects for the development of thick-seam mining technology in the southern Kuzbass
Authors: Vargolskikh Anastasia
Published: December 2021

The paper discusses the factors that limit the growth of coal production in Kuzbass. They were identified by the results of statistical analysis of the actual production indicators of working faces in eight thick coal seams. Technological solutions for the rational control of hard-to-break roof rocks, the shape and size of coal pillars, which ensure the stability of protected workings and isolation of the worked-out area from endogenous fires, are substantiated.
Longwall top coal caving automation concept
Authors: Nikitenko Sergey , Kiessling Ulf , Kizilov Sergey , Nikitenko Mikhail
Published: December 2021

This paper describes history of the longwall top coal caving technology. The devices capable to promote wider application of LTCC are discussed. The advantages, shortcomings and their elimination methods are specified. The authors designate the objectives to be met to implement the maximum potential of LTCC. The industry approach to these objectives is exemplified. The applicability of LTCC in combination with new-generation powered roof support with coal outlet in supported area in longwalls is discussed. The ways of finding solutions to the set problems are proposed.
Titanium effect on the microstructure and properties of the layer deposited by Fe-C-Si-Мn-Сr-Mo-Ni flux cored wire on the parts working in severe wear conditions
Authors: Kozyrev Nikolay , Mikhno Alexey , Usoltsev Aleksandr , Kibko Natalya , Kozyreva Olga
Published: December 2021

The study results of the structure and properties of the layer deposited with flux-cored wires of the Fe-C-Si-Mn-Cr-Mo-Ni system additionally alloyed with titanium are presented. Surfacing with the investigated flux-cored wires was carried out on a substrate made of 09G2S steel using silicomanganese slag flux.
Integration features of control systems in multi-complex distributed production
Authors: Makarov Georgiy , Myshlyaev Leonid , Slamatin Aleksandr , Vdovichenko Vladimir
Published: December 2021

Different options of the structure of automated process control system (APCS) are considered using the example of the coal preparation plant with a single automation platform Omron Sysmac, as well as with heterogeneous devices connected by industrial networks Ethernet/IP at several levels with physical separation. The general APCS structure is proposed. It is suitable for the end-to-end control of objects with variable structure, built from various technological complexes of coal preparation plants.
Operation modes of frequency converter in the rotor circuit of induction motor drive of a mine hoist
Authors: Ostrovlyanchik Viktor , Popolzin Ivan , Kubarev Vasiliy , Marshev Dmitriy , Qu Qiang
Published: December 2021

The electric drive of a hoist must ensure the formation of the required tachogram and the diagram of driving forces. The tachogram depends on the type of lifting vehicles. For hoist electric drives based on a wound-rotor induction motor, it is possible to use a frequency converter in the rotor circuit to control the motor speed and torque. When designing a converter, the problem arises of determining the operating modes of its bridges and the current direction between them. The article analyzes the operating modes of the hoisting motor in accordance with various sections of the tachogram of the unit and the connection between the mechanical and electrical coordinates of the drive. The analysis carried out in the work makes it possible to obtain and implement methods for determining the parameters of the frequency converter in the rotor circuit and developing an algorithm for controlling the converter bridges to ensure the required tachogram and driving force diagram.
Environmental aspects of the competitiveness strategy of mining enterprises in the context of sustainable development
Authors: Popelo Olha , Marhasova Viktoriia , Garafonova Olga , Grigashkina Svetlana
Published: December 2021

The article reveals the environmental aspects of the competitiveness strategies of mining enterprises in the context of ensuring sustainable development of the economy. The reasons as a result of which the state of the environment in the process of development of oil and gas fields worsens are investigated. The stages of search for exploration and development of oil and gas fields are considered. The negative impact on the environment component of sustainable development of prospecting and exploitation works on oil fields has been determined.
Der Tuberositas-Transfer im kindlichen Alter
Authors: Wagner Daniel
Published: December 2021

Die patellofemorale Instabilität (PFI) ist eine typische Erkrankung im Kindes- und Jugendalter. Aufgrund des hohen Reluxationsrisikos ist eine gezielte Risikoanalyse notwendig. Die Patella alta und eine veränderte Zugrichtung des Streckapparates, die über den TTTG-Abstand ermittelt werden kann, stellen auch im jungen Alter Hauptrisikofaktoren der PFI dar. Die zunehmend evidenzbasierte Indikationsstellung unterscheidet sich nicht wesentlich von der Erwachsener. Aufgrund der Gefahr einer gestörten Wachstumslenkung kann bei offenen Fugen ein Tuberositas-Transfer jedoch nicht erfolgen, sodass die operativen Techniken den Gegebenheiten angepasst werden müssen. Eine Korrektur der Patella alta und eines erhöhten TTTG-Abstands ist mit weichteiligen distalen Eingriffen ohne Beeinträchtigung der Wachstumsfugen auch im Kindes- und Jugendalter möglich und verbessert die Ergebnisse gegenüber isolierten MPFL-Rekonstruktionen bei Überschreiten von Grenzwerten der Risikofaktoren und korrekter Indikationsstellung.
Functional Assessment of Hearing Aid Benefit: Incorporating Verification and Aided Speech Recognition Testing into Routine Practice
Authors: Sydlowski Sarah A. , King Michelle , Petter Karen , Bachmann Meagan Lewis
Published: December 2021

Potential cochlear implant (CI) candidates arrive to the clinic with a variety of hearing loss configurations, hearing aid history, and aided capabilities. CI candidacy is primarily determined based on aided speech recognition capability, which relies on benefit derived from use of hearing aids. Therefore, contemporary evaluation for CI candidacy should incorporate a battery of testing to determine abilities and limitations and must be predicated on appropriate verification of the hearing aid fitting. However, recent reports, including a retrospective chart review of patients presenting to Cleveland Clinic for CI evaluation, suggest that a significant subset of patients may be using inappropriately fit or programmed amplification. Thus, a combination of simulated real-ear measurements and aided speech recognition testing is essential for fully assessing the effect of amplification and ultimately determination of CI candidacy. Furthermore, waiting to incorporate these tools until CI candidacy is suspected may delay timely identification of problems or need to change technology. Utilization of evidence-based decision drivers ultimately leads clinicians to timely patient-specific interventions which may include surgical intervention or other amplification options. As audiology moves into a healthcare era in which payers consider the benefit of our services to overall health and well-being, demonstrating timely, optimal outcomes using thorough, multifactorial evaluation is essential.
Numerical simulation of vacuum arc movement between transverse magnetic field contacts
Authors: Xiu Shixin , Jiang Yuzi , Liu Zixi , Liu Zhanpeng , Yang Jinwang , Qu Chenchen
Published: December 2021

The contact system of the vacuum switch is a crucial factor affecting the breaking performance of the vacuum switch. The study of the arc characteristics has significant impacts in improving the breaking ability of the vacuum switch. It is difficult to fully grasp the characteristics of the vacuum arc by experimental methods. The vacuum arc simulation model can obtain the internal parameters spatial distribution and motion characteristics more effectively. A high-current vacuum arc magnetohydrodynamic model was established, which considered the influence of ion and electron viscosity and the combined effect of the transverse magnetic field (TMF) and the axial magnetic field (AMF). The simulation obtained the plasma parameters of the arc column region as well as the temperature distribution characteristics of the cathode and anode surfaces. In addition, the changes in plasma parameters during arc movement under the action of different TMF and AMF components between TMF contacts were discussed. The simulation results are relatively consistent with the experimental results and the existing research results, which provide theoretical support for the research on the mechanism of vacuum arc motion characteristics.
A highly sensitive gas chromatograph for in situ and operando experiments on catalytic reactions
Authors: Golder Katharina M. , Böller Bernhard , Stienen Günter , Sickerling Joern , Wintterlin Joost
Published: December 2021

We describe an automated gas sampling and injection unit for a gas chromatograph (GC). It has specially been designed for low concentrations of products formed in catalytic in situ and operando experiments when slow reactions on single crystal models are investigated. The unit makes use of a buffer volume that is filled with gas samples from the reactor at a reduced pressure. The gas samples are then compressed by He to the injection pressure of 1000 mbar and pushed into two sample loops of the GC, without major intermixing with He. With an additional cryo trap at one of the GC column heads, the design aims at concentrating the gas samples and focusing the peaks. The performance is characterized by experiments on the Fischer–Tropsch synthesis, using H2/CO mixtures (syngas) at 200 and 950 mbar and a Co(0001) single crystal sample as model catalyst. Chromatograms recorded during the reaction display sharp, well separated peaks of saturated and unsaturated C1 to C4 hydrocarbons formed by the reaction, whereas the syngas matrix only gives moderate signals that can be well separated from the product peaks. Detection and quantification limits of 0.4 and 1.3 ppb, respectively, have been achieved and turnover numbers as low as 10−5 s−1 could be measured. The system can be combined with all known analysis techniques used in in situ and operando experiments.
Perspectives on self-powered respiration sensor based on triboelectric nanogenerator
Authors: Chen Yanmeng , Li Weixiong , Chen Chunxu , Tai Huiling , Xie Guangzhong , Jiang Yadong , Su Yuanjie
Published: December 2021

Triboelectric nanogenerators (TENGs) have attracted widespread attention in recent years due to outstanding energy converting capability enabled by the coupling between the triboelectric effect and electrostatic induction. The excellent energy harvesting ability of TENG under low frequency and slight amplitude endows a unique superiority for self-powered respiratory detection. This Perspective systematically reviews recent progress on TENG motivated self-powered respiratory sensors. First, based on the four working modes of TENG, two types of self-powered respiratory sensors are discussed, including physical behavior monitoring and chemical reagents detection. Furthermore, the sensing mechanism, sensitive materials, device structures, and related application were comprehensively analyzed. Finally, the existing problems and development opportunities of self-powered respiration monitoring based on the triboelectric effect are interpreted in detail.
Spin qubit based on the nitrogen-vacancy center analog in a diamond-like compound C3BN
Authors: Wang Duo , Liu Lei , Zhuang Houlong L.
Published: December 2021

The nitrogen-vacancy (NV) center in diamond plays important roles in emerging quantum technologies. Currently available methods to fabricate the NV center often involve complex processes such as N implantation. By contrast, in a diamond-like compound C3BN, creating a boron (B) vacancy immediately leads to an NV-center analog. We use the strongly constrained and appropriately normed semilocal density functional—this functional leads to nearly the same zero-phonon line (ZPL) energy as the experiment and as obtained from the more time-consuming hybrid density functional calculations—to explore the potential of this NV-center analog as a novel spin qubit for applications in quantum information processing. We show that the NV-center analog in C3BN possesses many similar properties to the NV center in diamond including a wide bandgap, weak spin–orbit coupling, an energetically stable negatively charged state, a highly localized spin density, a paramagnetic triplet ground state, and strong hyperfine interactions, which are the properties that make the NV center in diamond stand out as a suitable quantum bit (qubit). We also predict that the NV-center analog in C3BN exhibits two ZPL energies that correspond to longer wavelengths close to the ideal telecommunication band for quantum communications. C3BN studied here represents only one example of A3XY (A: group IV element; X/Y: group III/V elements) compounds. We expect many other compounds of this family to have similar NV-center analogs with a wide range of ZPL energies and functional properties, promising to be the new hosts of qubits for quantum technology applications. Furthermore, A3XY compounds often contain group IV elements such as silicon and germanium, so they are compatible with sophisticated semiconductor processing techniques. Our work opens up ample opportunities toward scalable qubit host materials and novel quantum devices.
Thermal desorption of structured water layer on epitaxial graphene
Authors: Minami Tomoki , Ochi Shuta , Nakai Hiroki , Kinoshita Tomohiro , Ohno Yasuhide , Nagase Masao
Published: December 2021

Thermal desorption of the structured water layer on graphene was observed in this study via electrical conductivity measurements. Specifically, a structured water layer was formed on the graphene surface via deionized water treatment, following which we examined the thermal desorption process of the layer using sheet resistance measurements. The water molecules acting as a p-type dopant were strongly adsorbed on graphene, forming a solid layer. Consequently, the layer was completely removed from the graphene surface at 300⁡°C. The thermal desorption spectrum of the structured water layer on graphene was quantitatively obtained by converting the measured sheet resistance to carrier density change.
Identification of bulk and interface state-induced threshold voltage instability in metal/SiNx(insulator)/AlGaN/GaN high-electron-mobility transistors using deep-level transient spectroscopy
Authors: Yao Yixu , Jiang Qimeng , Huang Sen , Wang Xinhua , Luo Xiaorong , Jin Hao , Guo Fuqiang , Yin Haibo , Shi Jingyuan , Jiang Haojie , Li Junfeng , Wang Wenwu , Shen Bo , Wei Ke , Liu Xinyu
Published: December 2021

The physical mechanism of threshold voltage (VTH) instability in AlGaN/GaN metal-insulator-semiconductor high electron mobility transistors (MIS-HEMTs) was identified via capacitance-mode deep-level transient spectroscopy characterization. MIS-HEMTs with low-pressure chemical vapor deposited (LPCVD) SiNx as the gate insulator feature two distinctive trap-emission transients. The initial transient corresponds to emission of states at the SiNx/AlGaN interface, and the extracted density of state exhibits an exponential decay distribution. The subsequent transient is revealed due to hybrid emission of the interface and bulk states from the LPCVD-SiNx gate insulator, which features an activation energy higher than 1.1 eV and a capture cross section that ranges between 1 × 10−11 and 1 × 10−10 cm2. The bulk states in the LPCVD-SiNx gate insulator become charged under high gate voltage overdrive, leading to severe VTH instability in GaN-based MIS-HEMTs.
Differing effects of productivity on home-range size and population density of a native and an invasive mammalian carnivore
Authors: Hamer Rowena P. , Andersen Georgina E. , Hradsky Bronwyn A. , Troy Shannon N. , Gardiner Riana Z. , Johnson Christopher N. , Jones Menna E.
Published: December 2021

Abstract Context Home-range size and population density characteristics are crucial information in the design of effective wildlife management, whether for conservation or control, but can vary widely among populations of the same species. Aims We investigate the influence of site productivity on home-range size and population density for Australian populations of the native, threatened spotted-tailed quoll (Dasyurus maculatus) and the alien and highly successful feral cat (Felis catus). Methods We use live trapping and fine-scale GPS tracking to determine the home-range size and population density for both species across five sites in Tasmania. Using these data, as well as published estimates for both species from across Australia, we model how these parameters change in response to productivity gradients. We also use the telemetry data to examine the energetic costs of increasing home-range size for both species. Key results For both species, decreasing site productivity correlates with lower population density, and in spotted-tailed quolls and female feral cats, it also correlates with larger home-range sizes. However, the relative magnitude of these changes is different. Feral cats show smaller increases in home-range size but larger decreases in population density relative to spotted-tailed quolls. Our results suggest that these differences may be because increases in home-range size are more costly for feral cats, demonstrated by larger increases in nightly movement for the same increase in home-range area. Conclusions We suggest that knowledge of both home-range size and population density is needed to accurately determine how species respond to habitat productivity, and inform effective management across their geographic range. Implications These results have clear management implications; for example, in our low-rainfall sites, an adult female spotted-tailed quoll requires up to five times the amount of habitat expected on the basis of previous studies, thus dramatically increasing the costs of conservation programs for this threatened native species. Conversely, productivity-driven differences of up to four-fold in feral cat population density would influence the resources required for successful control programs of this invasive species.
Contested compensation: the politics, economics and legal nuances of compensating white former commercial farmers in Zimbabwe
Authors: Moyo Philani
Published: December 2021

In July 2020, the government of Zimbabwe and white former commercial farmers signed a Global Compensation Deed agreement of US$3.5 billion. Under this deal, and in line with Section 295 (3) of the constitution, white former farmers are ‘entitled to compensation from the State only for improvements that were on the land when it was acquired’. This article questions the political, financial and legal rationale of this agreement. First, it argues that the compensation deal is ultra vires since there is no enabling act of parliament to support it as required by the constitution. Consequently, this deal is tenuous and insidious. Second, Zimbabwe’s economic implosion and colossal foreign debt will make it difficult for international financial institutions to extend credit lines. Third, this deal reverses some land reform outcomes, thus raising political tensions. Fourth, these political tensions are swelling into resistance against the deal by war veterans and the opposition.
Endosomal escape of delivered mRNA from endosomal recycling tubules visualized at the nanoscale
Authors: Paramasivam Prasath , Franke Christian , Stöter Martin , Höijer Andreas , Bartesaghi Stefano , Sabirsh Alan , Lindfors Lennart , Arteta Marianna Yanez , Dahlén Anders , Bak Annette , Andersson Shalini , Kalaidzidis Yannis , Bickle Marc , Zerial Marino
Published: December 2021

Delivery of exogenous mRNA using lipid nanoparticles (LNPs) is a promising strategy for therapeutics. However, a bottleneck remains in the poor understanding of the parameters that correlate with endosomal escape versus cytotoxicity. To address this problem, we compared the endosomal distribution of six LNP-mRNA formulations of diverse chemical composition and efficacy, similar to those used in mRNA-based vaccines, in primary human adipocytes, fibroblasts, and HeLa cells. Surprisingly, we found that total uptake is not a sufficient predictor of delivery, and different LNPs vary considerably in endosomal distributions. Prolonged uptake impaired endosomal acidification, a sign of cytotoxicity, and caused mRNA to accumulate in compartments defective in cargo transport and unproductive for delivery. In contrast, early endocytic/recycling compartments have the highest probability for mRNA escape. By using super-resolution microscopy, we could resolve a single LNP-mRNA within subendosomal compartments and capture events of mRNA escape from endosomal recycling tubules. Our results change the view of the mechanisms of endosomal escape and define quantitative parameters to guide the development of mRNA formulations toward higher efficacy and lower cytotoxicity.
The influence of axial offset of fusion splicing on a large mode area fiber based oscillator
Authors: Zhang Hanwei , Yang Baolai , Wang Peng , Xi Xiaoming , Shi Chen , Wang Xiaolin
Published: December 2021

Fiber oscillators have the potential for achieving high power, high beam quality lasers with simple and compact structure, of which the fusion splicing point is an important aspect to the laser output characteristics. A model taking into account the axial offset of the splicing point and spatial mode competition has been proposed to analyze the mode interaction of a large mode area fiber based oscillator. The calculated results show that the axial offset of the output side fusion point has the main influence on the laser output beam quality, but the axial offset would not obviously reduce the optical efficiency, especially when the value is smaller than 2 μm. The influence of cavity parameters on the laser output characteristics under the existence of splicing point with axial offset has also been discussed. This model can provide a method for analyzing the mode dynamic that may be helpful for understanding the mode interactions in fiber oscillators.
Role of electron correlations in some Weyl systems
Authors: Aryal Niraj , Manousakis Efstratios
Published: December 2021

We are discussing a model to understand previously obtained results on Weyl semimetals as realized in MoTe2 using DFT and DFT+U calculations. The model is motivated from general principles and we use it to investigate the effects of Coulomb correlations originating from the localized nature of the Mo-d orbitals. We find that such correlations can eliminate or create pairs of Weyl points as the strength of the Coulomb interaction is varied. The effect of the spin-orbit coupling (SOC) is to split each Weyl point, which is assumed present in the absence of SOC, into pairs of spin-chiral partners.
Some aspects of a two-pore translocation problem
Authors: Bhattacharya Aniket
Published: December 2021

We report Brownian dynamics (BD) simulation results for a coarse-grained (CG) model semi-flexible polymer threading through two nanopores. Particularly we study a “tug-of-war” situation where equal and opposite forces are applied on each pore to avoid folds for the polymer segment in between the pores. We calculate mean first passage times (MFPT) through the left and the right pores and show how the MFPT decays as a function of the off-set voltage between the pores. We present results for several bias voltages and chain stiffness. Our BD simulation results validate recent experimental results and offer avenues to further explore various aspects of multi-pore translocation problem using BD simulation strategies which we believe will provide insights to design new experiments.
Universal finite-size scaling function for coarsening in the Potts model with conserved dynamics
Authors: Janke Wolfhard , Majumder Suman , Das Subir K.
Published: December 2021

We study kinetics of phase segregation in multicomponent mixtures via Monte Carlo simulations of the q-state Potts model, in two spatial dimensions, for 2 ≤ q ≤ 20. The associated growth of domains in finite boxes, irrespective of q and temperature, can be described by a single universal finite-size scaling function, with only the introduction of a nonuniversal metric factor in the scaling variable. Our results show that although the scaling function is independent of the type of transition, the q-dependence of the metric factor hints to a crossover at q = 5 where the type of transition in the model changes from second to first order.
Research on Similar Animal Classification Based on CNN Algorithm
Authors: Zeng Peiyi
Published: December 2021

Animal image classification with CNN (convolutional neural network) is commonly investigated in aera of image recogniation and classification, but major studies focus on species pictures classification with obvious distinctions. For example, CNN is usually employed to distinghish images between dogs and cats. This article puts the effort on similar animal images classification by applying simple 2D CNN via python. It focus on the binary classification for snub-nosed monkeys and normal monkeys. This distinguishment is hard to be done manually in a short time. For constructing complete convolutional neural network, some preparations are done in advance, such as the database construction and preprocess. The database is constructed by python crawler (downloading from google images), with 800 and 200 images for each class respectively as train data and test data. The pre-work includes image resizing, decoding and standardization. After that, the model is trained and then tested for verifying the model reliability. The training accuracy is 96.67% without any abnormality. On the basis of successful training, the test accuracy almost coincides with train accuracy in each 50 generations and plots in a graph. It indicates similar trends and results for them in the whole process. Because of this, CNN model in the study can help people identify rare animals in time and then people can effectively protect them. Therefore, CNN will be helpful in field of animal conservation, especially for rare species.
A Survey of Deep Learning Approaches on Wind Turbine Condition Monitoring
Authors: Li Sijia
Published: December 2021

Current physics-based wind turbine monitoring methods often need extra sensors installed on wind turbines, thus increasing the operation and maintenance (O&M) cost. Besides, physical methods are only effective under some constraints. The real effectiveness needs to be further checked in real conditions. Recent advances in data acquisition systems allow collection of large volumes of operational data of wind turbines. Learning knowledge from the data allows us to do monitoring in another direction. In this paper, a survey of deep learning algorithms applied to wind turbine condition monitoring is given. Compared with original data, more meaning features were extracted through feature extraction of deep learning. Monitoring these new signals, outliers were detected by applying suitable control charts. Several industrial cases confirmed the effectiveness and efficiency of these frameworks.
Recognition of flying small target based on enhanced quadratic time-frequency analysis
Authors: Guo Jia , Huang Xiaohong
Published: December 2021

UAVs (Unmanned Aerial Vehicles, UAVs) are flying targets that sail at low altitudes, are slower and smaller in size. Nowadays, the task of detecting and distinguishing flying small targets is very difficult, so how to efficiently recognize flying small targets in real time is a key issue of current research. In order to solve this problem, this paper proposes a method of using pseudo-WVD and image fusion to represent the characteristics of UAVs. First, the SMMWR (Single-mode millimeter wave radar, SMMWR) equipment is used to collect the echo signals of various types of UAVs, and at the same time, the two-dimensional FFT is used to extract the target micro-motion signals in the distance dimension. Secondly, PWVD is used to generate time-frequency graphs of different window functions. Finally, the images fused based on principal component analysis are sent to AlexNet for training. The result proves that the accuracy of recognition rate based on AlexNet can be 93.75%.
Research on restoration method of nuclear pulse current signal of semiconductor detector based on artificial neural networks
Authors: Qin Zhang , Qin ZhangJian , Zhang JingLong , Qi XinTe
Published: December 2021

The charge pulse generated by semiconductor detector caused by nuclear event carries nuclide and nuclear reaction information, but the amplified charge pulse amplitude is obviously weak and the noise is so large. Aiming at the difficulty of obtaining the charge signal pulse generated by the detector, a method for recovering the nuclear pulse current signal of semiconductor detector is proposed. Pulse recovery is divided into two parts: pulse shape recovery and pulse amplitude recovery. Point at the pulse shape, a shape recognition network of nuclear pulse current signal based on deep learning is proposed. For pulse amplitude,it can be obtained by Mexican straw hat wavelet forming algorithm. This algorithm can eliminate the baseline fluctuation caused by pulse stacking. The proposed shape recognition network of nuclear pulse current signal is composed of classifier and regressor. The classifier is used to judge whether the data contains a complete rising edge. The data containing the complete rising edge is sent to the regressor for prediction, so as to obtain the parameters related to the current pulse shape. The precision, recall and F-Measure of the classifier in classifying the test set are 98.88%, 98.05% and 98.33%, respectively. The average absolute error of the regressor in predicting the parameters related to the current pulse shape is about 9 ns. The experimental results show that the proposed method can recover the shape and amplitude of the current signal.
Nondestructive Detection of Ceramic Products Based on Tapping Sound Signal Feature Recogition
Authors: Liu Liping , Jiang Liucheng , Qiao Lele
Published: December 2021

Recent studies on the test of ceramic non-destructive testing are mainly based on high cost technologies, image processing and so on, these method possesses some drawback of low efficiency, high cost and so on. What’s more, detecting whether the ceramic products by human through listening to sound of tapping is also effectless. This paper proposed a non-destructive method for ceramic products to solve this problem. This non-destructive method consists of a tapping device and a signal processing module. The tapping device will be applied to generate the tapping sound signal and the signal processing system will be applied to analysis signal. After the process of signal analysis, sample length and peak of spectrum 2 parameters is extracted, then use these parameters to train SVM, the results will be compared with BP neural network (BPNN). The result of experiment shows that SVM with different kernels of linear, poly, rbf, sigmoid respectively reach the accuracy of 96.29%, 96.29%, 46.29%, 93.82%, while BPNN reaches the accuracy of 93.21%. This result proves that SVM can effectively complete the task of identifying defective ceramics, and its performance is better than BPNN.
Research on Electromagnetic Compatibility of High Frequency Switching Power Supply Based on Harmonic Balance Finite Element Method
Authors: Bu Chunning , Zhang Zhihong , Hou Tiantian , Bai Xin , He Hong
Published: December 2021

With the rapid development of electronic technology, high frequency switching power supply has been widely used in various electrical equipment, and its electromagnetic interference has attracted more and more attention. In this paper, the harmonic balance finite element method is used to solve the electromagnetic compatibility of high frequency switching power supply. In this method, the coefficients of sine wave are applied to represent the waveform, and the solution is generated by linear synthesis. We propose to combine it with the finite element method to solve the steady-state response of electromagnetic field in frequency domain. It is proved the method we proposed is superior to the traditional time domain method.
Special Vehicles to Prevent Touching High-voltage Lines Monitoring and Warning Device
Authors: Zhao Tiemin , Liu Jianshu , Zheng Shiyang , Han Dongxu , Wang Junqi
Published: December 2021

Domestic regional special vehicles and construction personnel high-voltage electrocution accidents always occur, resulting in large-scale equipment and socio-economic losses. Based on this, in order to effectively reduce special vehicles touching high-voltage lines causing safety accidents, this paper researches and designs a safety monitoring and warning device for special vehicles touching high-voltage lines, mainly including sensor monitoring templates, signal transmission templates and monitoring and warning alert templates, through the decoding of different template principles, combined with electric field induction and wireless transmission principles, the safety distance of high-voltage lines is relevant to explore, then when Special vehicle objects into the safety distance threshold, that is, to start the information monitoring alarm, to remind the construction of special vehicle equipment and personnel away from electrocution, to ensure safe production. Through the monitoring and warning device, the rationalization, economy and safety of high-voltage line can be achieved.
Study on the Influence of Explosive Types on Rod Jet
Authors: Wang Bingzhe , Xie Liyun , Guo Zhounan
Published: December 2021

In order to study the influence of explosive type on the rod jet formation of energetic composite liner, the process of rod jet formation of this liner is numerically simulated by using finite element analysis and multi-material Euler algorithm. In this paper, the rod jet formation and penetration performance of the liner are studied and analyzed by combining relevant theories and simulation calculation, and the influence law of explosive type on rod jet formation and target penetration thickness is obtained. In this paper, the stability of rod jet formed by this kind of model is verified by numerical simulation, and the influence law of explosive type on rod jet is obtained by simulating the collected data such as effective mass, tip velocity and jet length of rod jet and the equivalent target penetration thickness obtained by the quasi steady incompressible ideal fluid theory of jet penetration; it provides data support and design basis for the application of new explosives in energetic composite liner in the next stage.