HetNets Under Decoupled Uplink and Downlink Access with UE Random Discontinuous Transmission: Local Delay and Energy Efficiency

Due to the limited uplink capability in heterogeneousnetworks (HetNets), the decoupled uplinkand downlink access (DUDA) mode has recently beenproposed to improve the uplink performance. In thispaper, the random discontinuous transmission (DTX)at user equipment (UE) is adopted to reduce the interferencecorrelation across different time slots. By utilizingstochastic geometry, we analytically derive themean local delay and energy efficiency (EE) of an uplinkHetNet with UE random DTX scheme under theDUDA mode. These expressions are further approximatedas closed forms under reasonable assumptions.Our results reveal that under the DUDA mode, there isan optimal EE with respect to mute probability underthe finite local delay constraint. In addition, with thesame finite mean local delay as under the coupled uplinkand downlink access (CUDA) mode, the HetNetsunder the DUDA mode can achieve a higher EE witha lower mute probability.

Layered Coded Cache Placement and Cooperative Delivery with Sharing Links in Satellite-Terrestrial Integrated Networks

Cooperative utilization of multidimensional resources including cache, power and spectrum in satellite-terrestrial integrated networks(STINs) can provide a feasible approach for massive streaming media content delivery over the seamless global coverage area. However, the on-board supportable resources of a single satellite are extremely limited and lack of interaction with others. In this paper, we design a network model with two-layered cache deployment, i.e., satellite layer and ground base station layer, and two types of sharing links, i.e., terrestrial-satellite sharing(TSS) links and inter-satellite sharing(ISS) links, to enhance the capability of cooperative delivery over STINs. Thus, we use rateless codes for the content divided-packet transmission, and derive the total energy efficiency(EE) in the whole transmission procedure, which is defined as the ratio of traffic offloading and energy consumption. We formulate two optimization problems about maximizing EE in different sharing scenarios(only TSS and TSS-ISS),and propose two optimized algorithms to obtain the optimal content placement matrixes, respectively.Simulation results demonstrate that, enabling sharing links with optimized cache placement have more than 2 times improvement of EE performance than other traditional placement schemes. Particularly, TSS-ISS schemes have the higher EE performance than only TSS schemes under the conditions of enough number of satellites and smaller inter-satellite distances.

“Half of the Node Records Are Forged?”: The Problemof Node Records Forgery in Ethereum Network

Ethereum, currently the most widely utilized smart contracts platform, anchors the security of myriad smartcontracts upon its own robustness. Its foundational peer-to-peer network facilitates a dependable node connectionmechanism, whereas an efficient data-sharing protocol constitutes as the bedrock of Blockchain network security.In this paper, we propose NodeHunter, an Ethereum network detector implemented through the application ofsimulation technology, which is capable of aggregating all node records within the network and the interconnectednessbetween them. Utilizing this connection information, NodeHunter can procure more comprehensive insightsfor network status analysis compared to preceding detection methodologies. Throughout a three-month period ofunbroken surveillance of the Ethereum network, we obtained an excess of two million node records along with overone hundred million node acquaintances. Analysis of the gathered data revealed that an alarming 49% or more ofthese node records were maliciously forged.

Energy Harvesting in the Wake of An Inverted C-Shaped Bluff Body

This paper proposes a novel wake-induced vibration(WIV)-based energy harvesting system consisting of two bluff bodies.An inverted C-shaped bluff body is stationary installed at the upstream position to generate an interference wake street,and a cylinder bluff body equipped with a transducer is elastically suspended at the downstream position to harness WIV energy.The hydrodynamics and energy harvesting(EH)performance of the proposed system are investigated via experimental studies.The reduced velocity(U*)ranging from 2 to 14(the corresponding Reynolds number ranging from 15100 to 106200)is considered in the present study.It is found that the wake generated by the inverted C-shaped bluff body significantly affects the EH performance.Enlarging the opening angle(α)of the C-shaped bluff body increases the vibration amplitude of the downstream cylinder,thereby increasing the harvested power.When the spacing(L)between two bluff bodies is two times the cylinder diameter(D),the wake-induced vibration(WIV)mode is observed,while the combined WIV and wake galloping(WG)mode occurs whenαis 150°,and L equals 3D or 4D.The average drag coefficient becomes negative when L is 2D,3D,or 4D.By carefully configuring a C-shaped bluff body,the wake generated by it can bring an augmenting effect on the vibration of the downstream EH cylinder.For example,the RMS power output of the proposed EH system reaches a maximum of 0.31 W at U*=8 and L=4D,which is 300%greater than that of its traditional counterpart.Furthermore,after a number of case stud-ies,it is identified that the proposed EH system can achieve the best performance whenαis 150°and L=2D.

八步连续流全合成维生素B_(1)工艺研究

Vitamin B_(1) is widely applied in the healthcare and food industry as an antineuritic and antioxidant to maintain the normal functioning of nerve conduction,the heart,and the gastrointestinal tract.This study reports on an integrated eight-step continuous-flow synthesis of vitamin B_(1) from commercially available 2-cyanoacetamide.The proposed continuous-flow process is based on advances in chemistry,engineering,and equipment design,and affords improved performance and safety compared with batch-mode manufacturing.Several challenges were precisely investigated and controlled,including mixing,unexpected clogging,solvent switches,an exothermic reaction,and the prevention of side reactions,using various micro-channel flow reactors,mixers,separators,and continuous filters.Vitamin B_(1) was produced with a separated yield of 47.7% and high purity,with a total residence time of about 3.5 h.This eight-step continuous-flow protocol enables technology involving up to six of the key principles of green chemistry.Hence,the application of flow technology is of paramount importance for improving security,reducing waste,and,in particular,improving the efficiency of batch operations that require several days for manufacturing.

揭示氨对正己酸生产影响的机制——影响途径、关键酶和微生物

n-Caproate,which is produced via chain elongation(CE)using waste biomass,can supply various fossilderived products,thus advancing the realization of carbon neutrality.Ammonia released from the degradation of nitrogen-rich waste biomass can act as a nutrient or an inhibitor in anaerobic bioprocesses,including CE,with the distinction being primarily dependent on its concentration.Currently,the optimal concentration of ammonia and the threshold of toxicity for open-culture n-caproate production using ethanol as an electron donor,along with the underlying mechanisms,remain unclear.This study revealed that the optimal concentration of ammonia for n-caproate production was 2.0 g∙L^(-1),whereas concentrations exceeding this threshold markedly suppressed the CE performance.Exploration of the mechanism revealed the involvement of two forms of ammonia(i.e.,ammonium ions and free ammonia)in this inhibitory behavior.High ammonia levels(5.0 g∙L^(-1))induced excessive ethanol oxidation and suppressed the reverse β-oxidation(RBO)process,directly leading to the enhanced activities of enzymes(phosphotransacetylase and acetate kinase)responsible for acetate formation and diminished activities of butyryl-coenzyme A(CoA):acetyl-CoA transferase,caproyl-CoA:butyryl-CoA transferase,and caproyl-CoA:acetyl-CoA transferase that are involved in the syntheses of n-butyrate and n-caproate.Furthermore,the composition of the microbial community shifted from Paraclostridium dominance(at 0.1 g∙L^(-1)ammonia)to a co-dominance of Fermentimonas,Clostridium sensu stricto 12,and Clostridium sensu stricto 15 at 2.0 g∙L^(-1)ammonia.However,these CE-functional bacteria were mostly absent in the presence of excessive ammonia(5.0 g∙L^(-1)ammonia).Metagenomic analysis revealed the upregulation of functions such as RBO,fatty acid synthesis,K^(+)efflux,adenosine triphosphatase(ATPase)metabolism,and metal cation export in the presence of 2.0 g∙L^(-1)ammonia,collectively contributing to enhanced n-caproate production.Conversely,the aforementioned functions(excluding metal cation export)and K^(+)influx were suppressed by excessive ammonia,undermining both ammonia detoxification and n-caproate biosynthesis.The comprehensive elucidation of ammonia-driven mechanisms influencing n-caproate production,as provided in this study,is expected to inspire researchers to devise effective strategies to alleviate ammonia-induced inhibition.

A Stroke-Limitation AMD Control System with Variable Gain and Limited Area for High-Rise Buildings

Collisions between a moving mass and an anti-collision device increase structural responses and threaten structural safety.An active mass damper(AMD)with stroke limitations is often used to avoid collisions.However,a strokelimited AMD control system with a fixed limited area shortens the available AMD stroke and leads to significant control power.To solve this problem,the design approach with variable gain and limited area(VGLA)is proposed in this study.First,the boundary of variable-limited areas is calculated based on the real-time status of the moving mass.The variable gain(VG)expression at the variable limited area is deduced by considering the saturation of AMD stroke.Then,numerical simulations of a stroke-limited AMD control system with VGLA are conducted on a high-rise building structure.These numerical simulations show that the proposed approach has superior strokelimitation performance compared with a stroke-limited AMD control system with a fixed limited area.Finally,the proposed approach is validated through experiments on a four-story steel frame.

Modified filter for mean elements estimation with state jumping

To investigate the real-time mean orbital elements(MOEs)estimation problem under the influence of state jumping caused by non-fatal spacecraft collision or protective orbit trans-fer,a modified augmented square-root unscented Kalman filter(MASUKF)is proposed.The MASUKF is composed of sigma points calculation,time update,modified state jumping detec-tion,and measurement update.Compared with the filters used in the existing literature on MOEs estimation,it has three main characteristics.Firstly,the state vector is augmented from six to nine by the added thrust acceleration terms,which makes the fil-ter additionally give the state-jumping-thrust-acceleration esti-mation.Secondly,the normalized innovation is used for state jumping detection to set detection threshold concisely and make the filter detect various state jumping with low latency.Thirdly,when sate jumping is detected,the covariance matrix inflation will be done,and then an extra time update process will be con-ducted at this time instance before measurement update.In this way,the relatively large estimation error at the detection moment can significantly decrease.Finally,typical simulations are per-formed to illustrated the effectiveness of the method.

Localization and Evaluation of Motor Vehicle Emission Simulator (MOVES) Model for Predicting the Emissions of Private Cars:a Case Study of Shenzhen City,China

Motor Vehicle emission simulator(MOVES)model was localized by changing the base emission rates in MySQL database of the model,and using the actual measured data for private cars in Shenzhen City,China.The performances of localized MOVES model and non-localized MOVES model were evaluated by comparing the predicted emission factors to the measured ones.The results showed that by localization of the base emission rates,the prediction accuracy of the localized MOVES model for hydrocarbon(HC)and nitrogen oxides(NO x)was significantly improved.The accuracy of the localized MOVES model simulations in the Opmode increased by 86%,88%and 71%for HC,76%,42%and 72%for NO x on arterial roads,expressways and highways.For carbon monoxide(CO),however,the simulation performance based on the average velocity mode on expressways and highways became poor after localization,with the decrease of 28%and 8%respectively.Overall,by the localization of the base emission rates,the relative errors of the simulated emission factors of HC,CO and NO x of private cars were less than 37%.

The Phenomenon of Near-home Office and the Supported Space:Evidence from Shenzhen’s Employees

At present,working near home has gradually become prominent.This paper uses a fieldwork approach to investigate the characteristics and motivations of near-home office,and introduce and evaluates the support of near-home office space in Shenzhen.Commonly,the near-home office workers have three behavioral characteristics;Activating in the community;Working flexibly;and Blending life with work.With the development of the office concept and mobile information technology,more people choose and prefer near-home office,especially during the COVID-19 pandemic.The near-home office space provides working environment and services;however,the near-home office space needs to be improved.This study indicates that near-home office may play an important role in the future,therefore more studies are required in the future focusing on this aspect.

Observation of Medical Anthropology on Covid-19 Variants Epidemic Prevention Based on the Community-Level Governance Experience of Shenzhen in 2022

In recent years,the thinking and research on the prevention and control of Covid-19 Variants Epidemic is not only the technical operation level discussion in the public health and disease prevention academic circles,there is also growing academic interest in comparative research on public health governance and different paradigms.Based on the experience of Shenzhen's epidemic prevention and control team at the community governance level in 2022,based on the observational perspective of medical anthropology,and through comparison with Hong Kong's anti-epidemic experience,this paper deeply analyzes the function and impact of traditional medical methods in epidemic prevention and control.Then the authors cite the paradigm of‘systems medicine’and research results in recent years,closely link the research topic with community governance in methodological sense,so as to promote public health and epidemic prevention research that aim at the combination of technology and humanities.

A Revelation about the Enterprise of Innovation and Development of Shenzhen City—Based on the Perspective of Informal Economy and Informality

Related to the academic topic on innovation and development of information-communication industries,a dualist distinction between formal and informal economy has drawn a lot of research interests in the academy circle in recent years.In this essay,we discussed the background of Shenzhen’s leapfrog development as a Chinese economic special zone thanks to several policy advantages and the endeavor of itself as a principal part in the framework of China’s market economy reform.Despite the problem of informal economy for citizen’s living,we mainly focused on the positive effect of Shenzhen’s informal economy as flexibility of capital-labor effective coordination.Based on the analysis of the evolution of Shenzhen’s city construction and industrial development,and the analysis on the four development stages that Shenzhen had witnessed,we expect more practical and theoretical summary of its experience for all the developing countries.

Fabrication of Gd_(2)O_(3)-doped CeO_(2)thin films through DC reactive sputtering and their application in solid oxide fuel cells

Physical vapor deposition(PVD)can be used to produce high-quality Gd_(2)O_(3)-doped CeO2(GDC)films.Among various PVD methods,reactive sputtering provides unique benefits,such as high deposition rates and easy upscaling for industrial applications.GDC thin films were successfully fabricated through reactive sputtering using a Gd_(0.2)Ce_(0.8)(at%)metallic target,and their application in solid oxide fuel cells,such as buffer layers between yttria-stabilized zirconia(YSZ)/La0.6Sr0.4Co0.2Fe0.8O_(3−δ)and as sublayers in the steel/coating system,was evaluated.First,the direct current(DC)reactive-sputtering behavior of the GdCe metallic target was determined.Then,the GDC films were deposited on NiO-YSZ/YSZ half-cells to investigate the influence of oxygen flow rate on the quality of annealed GDC films.The results demonstrated that reactive sputtering can be used to prepare thin and dense GDC buffer layers without high-temperature sintering.Furthermore,the cells with a sputtered GDC buffer layer showed better electrochemical performance than those with a screen-printed GDC buffer layer.In addition,the insertion of a GDC sublayer between the SUS441 interconnects and the Mn-Co spinel coatings contributed to the reduction of the oxidation rate for SUS441 at operating temperatures,according to the area-specific resistance tests.

Time-sequential color code division multiplexing holographic display with metasurface

Color metasurface holograms are powerful and versatile platforms for modulating the amplitude,phase,polarization,and other properties of light at multiple operating wavelengths.However,the current color metasurface holography can only realize static manipulation.In this study,we propose and demonstrate a multiplexing metasurface technique combined with multiwavelength code-division multiplexing(CDM)to realize dynamic manipulation.Multicolor code references are utilized to record information within a single metasurface and increase the information capacity and security for anticracks.A total of 48 monochrome images consisting of pure color characters and multilevel color video frames were reconstructed in dual polarization channels of the birefringent metasurface to exhibit high information density,and a video was displayed via sequential illumination of the corresponding code patterns to verify the ability of dynamic manipulation.Our approach demonstrates significant application potential in optical data storage,optical encryption,multiwavelengthversatile diffractive optical elements,and stimulated emission depletion microscopy.

Inverse design for material anisotropy and its application for a compact X-cut TFLN on-chip wavelength demultiplexer

Inverse design focuses on identifying photonic structures to optimize the performance of photonic devices.Conventional scalar-based inverse design approaches are insufficient to design photonic devices of anisotropic materials such as lithium niobate(LN).To the best of our knowledge,this work proposes for the first time the inverse design method for anisotropic materials to optimize the structure of anisotropic-material based photonics devices.Specifically,the orientation dependent properties of anisotropic materials are included in the adjoint method,which provides a more precise prediction of light propagation within such materials.The proposed method is used to design ultra-compact wavelength division demultiplexers in the X-cut thin-film lithium niobate(TFLN)platform.By benchmarking the device performances of our method with those of classical scalar-based inverse design,we demonstrate that this method properly addresses the critical issue of material anisotropy in the X-cut TFLN platform.This proposed method fills the gap of inverse design of anisotropic materials based photonic devices,which finds prominent applications in TFLN platforms and other anisotropicmaterial based photonic integration platforms.

Deep learning:Applications,architectures,models,tools,and frameworks:A comprehensive survey

Deep Learning(DL)is a subfield of machine learning that significantly impacts extracting new knowledge.By using DL,the extraction of advanced data representations and knowledge can be made possible.Highly effective DL techniques help to find more hidden knowledge.Deep learning has a promising future due to its great performance and accuracy.We need to understand the fundamentals and the state‐of‐the‐art of DL to leverage it effectively.A survey on DL ways,advantages,drawbacks,architectures,and methods to have a straightforward and clear understanding of it from different views is explained in the paper.Moreover,the existing related methods are compared with each other,and the application of DL is described in some applications,such as medical image analysis,handwriting recognition,and so on.

Experimental study of a neutralizer-free gridded ion thruster using radio-frequency self-bias effect

An experimental study on the quasi-neutral beam extracted by a neutralizer-free gridded ion thruster prototype was presented.The prototype was designed using an inductively coupled plasma source terminated by a double-grid accelerator.The beam characteristics were compared when the accelerator was radio-frequency(RF)biased and direct-current(DC)biased.An RF power supply was applied to the screen grid via a blocking capacitor for the RF acceleration,and a DC power supply was directly connected to the screen grid for the DC acceleration.Argon was used as the propellant gas.Furthermore,the characteristics of the plasma beam,such as the floating potential,the spatial distribution of ion flux,and the ion energy distribution function(IEDF)were measured by a four-grid retarding field energy analyzer.The floating potential results showed that the beam space charge is compensated in the case of RF acceleration without a neutralizer,which is similar to the case of classical DC acceleration with a neutralizer.The ion flux of RF acceleration is 1.17 times higher than that of DC acceleration under the same DC component voltage between the double-grid.Moreover,there are significant differences in the beam IEDFs for RF and DC acceleration.The IEDF of RF acceleration has a widened and multipeaked profile,and the main peak moves toward the high-energy region with increasing the DC self-bias voltage.In addition,by comparing the IEDFs with RF acceleration frequencies of3.9 and 7.8 MHz,it is found that the IEDF has a more centered main peak and a narrower energy spread at a higher frequency.

BIFURCATION ANALYSIS IN A PREDATOR-PREY MODEL WITH AN ALLEE EFFECT AND A DELAYED MECHANISM

Regarding delay-induced predator-prey models, much research has been done on delayed destabilization, but whether delays are stabilizing or destabilizing is a subtle issue. In this study, we investigate predator-prey dynamics affected by both delays and the Allee effect. We analyze the consequences of delays in different feedback mechanisms. The existence of a Hopf bifurcation is studied, and we calculate the value of the delay that leads to the Hopf bifurcation. Furthermore, applying the normal form theory and a center manifold theorem, we consider the direction and stability of the Hopf bifurcation. Finally, we present numerical experiments that validate our theoretical analysis. Interestingly, depending on the chosen delay mechanism, we find that delays are not necessarily destabilizing. The Allee effect generally increases the stability of the equilibrium, and when the Allee effect involves a delay term, the stabilization effect is more pronounced.

Facile construction of a multilayered interface for a durable lithium‐rich cathode

Layered lithium-rich manganese-based oxide(LRMO)has the limitation of inevitable evolution of lattice oxygen release and layered structure transformation.Herein,a multilayer reconstruction strategy is applied to LRMO via facile pyrolysis of potassium Prussian blue.The multilayer interface is visually observed using an atomic-resolution scanning transmission electron microscope and a high-resolution transmission electron microscope.Combined with the electrochemical characterization,the redox of lattice oxygen is suppressed during the initial charging.In situ X-ray diffraction and the high-resolution transmission electron microscope demonstrate that the suppressed evolution of lattice oxygen eliminates the variation in the unit cell parameters during initial(de)lithiation,which further prevents lattice distortion during long cycling.As a result,the initial Coulombic efficiency of the modified LRMO is up to 87.31%,and the rate capacity and long-term cycle stability also improved considerably.In this work,a facile surface reconstruction strategy is used to suppress vigorous anionic redox,which is expected to stimulate material design in high-performance lithium ion batteries.

Numerical study of the radio-frequency biased accelerating system in ion thrusters

A 2D-3V implicit immersed-finite-element particle-in-cell(IFE-PIC)model is introduced to investigate the radio-frequency(RF)self-bias accelerating system applied in the RF ion thruster.A set of holes in a two-grid system with slit apertures is simulated in Cartesian coordinates.The characteristics of the plasma plume,such as the ion density,the neutralization rate and the ion and electron current density were investigated for different RF voltage amplitudes(600-1200V)and frequencies(6-30 MHz).Furthermore,the performance of the thruster was also carefully studied.The simulation results show that a well-focused plasma beam can be formed when the voltage amplitude is larger than 900 V and the frequency exceeds the reciprocal of ion transit time(≥12 MHz)in our simulation cases.The performance of the system can be evidently improved by increasing the voltage amplitude and the frequency,and the losses of the particle and thrust are reduced correspondingly.The bulk region of the plasma beam downstream shows good quasi-neutrality,and the ions are dominant in the peripheral region when a well-focused state is achieved.The high ion density beamlet in the periphery of the ion beam is closer to the axis when the voltage amplitude is increasing,while it is expanded radially when increasing the frequency.Backstream electrons have been observed upstream,and this mainly occurs in the phase in which the electron cannot escape.