Improved Segmented Belief Propagation List Decoding for Polar Codes with Bit-Flipping

Belief propagation list(BPL) decoding for polar codes has attracted more attention due to its inherent parallel nature. However, a large gap still exists with CRC-aided SCL(CA-SCL) decoding.In this work, an improved segmented belief propagation list decoding based on bit flipping(SBPL-BF) is proposed. On the one hand, the proposed algorithm makes use of the cooperative characteristic in BPL decoding such that the codeword is decoded in different BP decoders. Based on this characteristic, the unreliable bits for flipping could be split into multiple subblocks and could be flipped in different decoders simultaneously. On the other hand, a more flexible and effective processing strategy for the priori information of the unfrozen bits that do not need to be flipped is designed to improve the decoding convergence. In addition, this is the first proposal in BPL decoding which jointly optimizes the bit flipping of the information bits and the code bits. In particular, for bit flipping of the code bits, a H-matrix aided bit-flipping algorithm is designed to enhance the accuracy in identifying erroneous code bits. The simulation results show that the proposed algorithm significantly improves the errorcorrection performance of BPL decoding for medium and long codes. It is more than 0.25 d B better than the state-of-the-art BPL decoding at a block error rate(BLER) of 10^(-5), and outperforms CA-SCL decoding in the low signal-to-noise(SNR) region for(1024, 0.5)polar codes.

Research on Flexible Job Shop Scheduling Optimization Based on Segmented AGV

As a typical transportation tool in the intelligent manufacturing system,Automatic Guided Vehicle(AGV)plays an indispensable role in the automatic production process of the workshop.Therefore,integrating AGV resources into production scheduling has become a research hotspot.For the scheduling problem of the flexible job shop adopting segmented AGV,a dual-resource scheduling optimization mathematical model of machine tools and AGVs is established by minimizing the maximum completion time as the objective function,and an improved genetic algorithmis designed to solve the problem in this study.The algorithmdesigns a two-layer codingmethod based on process coding and machine tool coding and embeds the task allocation of AGV into the decoding process to realize the real dual resource integrated scheduling.When initializing the population,three strategies are designed to ensure the diversity of the population.In order to improve the local search ability and the quality of the solution of the genetic algorithm,three neighborhood structures are designed for variable neighborhood search.The superiority of the improved genetic algorithmand the influence of the location and number of transfer stations on scheduling results are verified in two cases.

Petroleum Retention,Intraformational Migration and Segmented Accumulation within the Organic-rich Shale in the Cretaceous Qingshankou Formation of the Gulong Sag,Songliao Basin,Northeast China

In this study,organic geochemical and petrological analyses were conducted on 111 shale samples from a well to understand the retention,intraformational migration and segmented accumulation(shale oil enrichment in different intervals is unconnected)features of shale oil within the organic-rich shale in the Qingshankou Formation of the Gulong Sag.Our study shows that retained petroleum characteristics in the investigated succession are mainly influenced by three factors:organic richness,intraformational migration and segmented accumulation.Organic matter richness primarily controls the amount of retained petroleum,especially the‘live’component indicated by the S_(2)value rather than the total organic carbon(TOC)figure alone.The negative expulsion efficiencies determined by mass-balance calculations of hydrocarbons reveal that petroleum from adjacent organic-rich intervals migrates into the interval of about 2386-2408 m,which is characterized by high free hydrocarbon(S_(1)),OSI and saturated hydrocarbons content,along with a greater difference inδ^(13)C values between polar compounds(including resins and asphaltenes)and saturated hydrocarbons.The depth-dependent heterogeneity of carbon isotope ratios(δ^(13)C)of mud methane gas,δ^(13)C of extracts gross composition(SARA),δ^(13)C of kerogen and SARA content of extracts suggest that the studied succession can be subdivided into four intervals.The shale oil sealing enrichment character in each interval is further corroborated by the distinctδ^(13)C values of mud methane gas in different intervals.Due to the migration of petroleum into the 2386-2408 m interval,the S_(1),OSI and saturated hydrocarbons content of the interval show higher relative values.The maturity of organic matter in the 2471-2500 m interval is at the highest with the smaller size molecular components of the retained petroleum.Thus,favorable‘sweet spots’may be found in the 2386-2408 m interval and the 2471-2500 m interval,according to the experiment results in this study.

Micro-Sized Pinhole Inspection with Segmented Time Reversal and High-Order Modes Cluster Lamb Waves Based on EMATs

Pinhole corrosion is difficult to discover through conventional ultrasonic guided waves inspection,particularly for micro-sized pinholes less than 1 mm in diameter.This study proposes a new micro-sized pinhole inspection method based on segmented time reversal(STR)and high-order modes cluster(HOMC)Lamb waves.First,the principle of defect echo enhancement using STR is introduced.Conventional and STR inspection experiments were conducted on aluminum plates with a thickness of 3 mm and defects with different diameters and depths.The parameters of the segment window are discussed in detail.The results indicate that the proposed method had an amplitude four times larger than of conventional ultrasonic guided waves inspection method for pinhole defect detection and could detect micro-sized pinhole defects as small as 0.5 mm in diameter and 0.5 mm in depth.Moreover,the segment window location and width(5-10 times width of the conventional excitation signal)did not affect the detection sensitivity.The combination of low-power and STR is more conducive to detection in different environments,indicating the robustness of the proposed method.Compared with conventional ultrasonic guided wave inspection methods,the proposed method can detect much smaller defect echoes usually obscured by noise that are difficult to detect with a lower excitation power and thus this study would be a good reference for pinhole defect detection.

Classification of hepatobiliary scintigraphy patterns in segmented gallbladder according to anatomical discordance

BACKGROUND Hepatobiliary scintigraphy(HBS)is a useful diagnostic imaging technique that uses radiotracers to evaluate the function of the gallbladder(GB)and biliary system.In segmented GB,some HBS images reveal a discordant GB boundary as compared to anatomical images.AIM To evaluate the characteristics of HBS in segmented GB and determine the clinical relevance according to HBS characteristics.METHODS A total of 268 patients with chronic cholecystitis,gallstones,or biliary colic symptoms who underwent HBS between 2011 and 2020 were enrolled.Segmented GB was defined as segmental luminal narrowing of the GB body on computed tomography(CT)or magnetic resonance(MR)images,and HBS was examined 1 mo before or after CT or MR.Segmented GB was classified into 3 types based on the filling and emptying patterns of the proximal and distal segments according to the characteristics of HBS images,and GB ejection fraction(GBEF)was identified:Type 1 was defined as a normal filling and emptying pattern;Type 2 was defined as an emptying defect on the distal segment;and Type 3 was defined as a filling defect in the distal segment.RESULTS Segmented GB accounted for 63 cases(23.5%),including 36 patients(57.1%)with Type 1,18 patients(28.6%)with Type 2,and 9 patients(14.3%)with Type 3 emptying pattern.Thus,approximately 43%of HBS images showed a discordant pattern as compared to anatomical imaging of segmented GB.Although there were no significant differences in clinical symptoms,rate of cholecystectomy,or pathological findings based on the type,most gallstones occurred in the distal segment.Reported GBEF was 62.50%±24.79%for Type 1,75.89%±17.21%for Type 2,and 88.56%±7.20%for Type 3.Type 1 showed no difference in reported GBEF compared to the non-segmented GB group(62.50%±24.79%vs 67.40%±21.78%).In contrast,the reported GBEF was higher in Types 2 and 3 with defective emptying and filling when compared to Type 1(80.11%±15.70%vs 62.57%±24.79%;P=0.001).CONCLUSION In segmented GB,discordance in the filling patterns detected by HBS and anatomical imaging could lead to misinterpretation of GBEF.For this reason,clinicians should be cautious when interpreting HBS results in patients with segmented GB.

Accuracy of eight intraocular lens power calculation formulas for segmented multifocal intraocular lens

AIM:To evaluate the accuracy of eight different intraocular lens(IOL)power calculation formulas for a segmented multifocal IOL.METHODS:A total of 53 eyes of 41 adult cataract patients who underwent phacoemulsification and implantation with the SBL-3 segmented multifocal IOL between January 1,2017 and January 31,2019 were included in this retrospective study.Preoperative biometry measurements were obtained using an IOL Master.Manifest refraction was performed at least 4 wk postoperatively.Accuracy of the eight formulas[Barrett Universal II,Emmetropia Verifying Optical(EVO),Haigis,Hill-RBF 2.0,Hoffer Q,Holladay 1,Kane,and SRK/T]was analyzed.RESULTS:Using current lens constants,all formulas exhibited errors of slight myopic shift in refractive prediction.The Barrett Universal II formula had a significantly lower median absolute error(MedAE)than did Holladay 1(P=0.02),Kane(P=0.001)and Hill-RBF 2.0(P<0.001)formulas.The Haigis formula had a lower MedAE value than did the Hill-RBF 2.0 formula(P=0.005).Differences in MedAE values among SRK/T,EVO and Hoffer Q formulas were not significant.After optimizing lens constants,the MedAE values of all formulas were reduced;significant changes were noted for EVO(P=0.022),Haigis(P=0.048);Hill-RBF 2.0(P=0.014),Holladay 1(P=0.045)and Kane(P=0.022)formulas.All formulas performed equally well after optimization of lens constants(P=0.203).CONCLUSION:All eight formulas tend to result in a myopic shift when using current lens constants.Optimized lens constants improve the accuracy of these formulas among adult Chinese patients.

LPI radar signal detection based on the combination of FFT and segmented autocorrelation plus PAHT

This paper proposes a desirable method to detect different kinds of low probability of intercept (LPI) radar signals, targeted at the main intra-pulse modulation method of LPI radar signals including the signals of linear frequency modulation, phase code, and frequency code. Firstly, it improves the coherent integration of LPI radar signals by adding the periodicity of the ambiguity function. Then, it develops a frequency domain detection method based on fast Fourier transform (FFT) and segmented autocorrelation function to detect signals without features of linear frequency modulation by virtue of the distribution characteristics of noise signals in the frequency domain. Finally, this paper gives a verification of the performance of the method for different signal-to-noise ratios by conducting simulation experiments, and compares the method with existing ones. Additionally, this method is characterized by the straightforward calculation and high real-time performance, which is conducive to better detecting all kinds of LPI radar signals.

Design and Optimization of Segmented PM Consequent Pole Hybrid Excited Flux Switching Machine for EV/HEV Application

Hybrid Excited Flux Switching Machines(HEFSMs)unique feature of high torque density(T_(den))of Permanent Magnet(PM)machines and flux regulation capability of wound field excitation machines.Due to aforesaid unique features,stator active HEFSMs are preferred for EV/HEV applications.In this paper a new Segmented PM Consequent Pole HE-FSM(SPMCPHEFSM)with flux bridge is proposed for EV/HEV.The developed SPMCPHEFSM exhibits improved flux modulation and flux regulation capability at reduced PM usage(suppressed PM volume by 46.52%and PM cost by 46.48%)and eliminating stator leakage flux.First,SPMCPHEFSM is geometric optimized(GO)for investigating influence of leading design with key performance indicators such as flux linkage(Ф_(pp)),average torque(T_(avg)),cogging torque(T_(cog)),T_(den),average power(P_(avg))and power density(P_(den))and then proceeded optimized model to structure modification for optimal stator design and position of field excitation coils(FEC).Comprehensive performance analysis reveals that the developed SPMCPHEFSM show improvedФ_(pp)maximum up to 9.11%,improved T_(avg)maximum up to 23.63%,truncate T_(cog)up to 18.9%whereas T_(den)and P_(den)are boost up to 23.55%and 89.72%respectively.

Effect of Segmented Electrode Length on the Performances of an Aton-Type Hall Thruster

The influences of the low-emissive graphite segmented electrode t）laeed near the channel exit on the discharge characteristics of a Hall thruster are studied using the particle- in-cell method. A two-dimensional physical model is established according to the Hall thruster discharge channel configuration. The effects of electrode length on the potential, ion density, electron temperature, ionization rate and discharge current are investigated. It is found that, with tile increasing of the segmented electrode length, the equipotential lines bend towards the channel exit. and approximately parallel to the wall at the channel surface, the radial velocity and radial flow of ions are increased, and the electron temperature is also enhanced. Due to the conductive characteristic of electrodes, the radial electric field and the axial electron conductivity near the wall are enhanced, and the probability of the electron-atom ionization is reduced, which leads to the degradation of the ionization rate in the discharge channel. However, the interaction between electrons and the wall enhances the near wall conductivity, therefore the discharge current grows along with the segmented electrode length, and the performance of the thruster is also affected.

Seismic Analysis of the Connections of Buried Segmented Pipes

Seismic analysis of buried pipes has been one study focus during the last decades,but the systematic seismic research of pipe connections,especially its relationship with the connected straight pipe,is nearly blank.On the basis,the influence of pipe connections on the joint deformations(JDs)of buried segmented pipes is analyzed in detail by considering different parameters,namely,connection shapes,ground conditions,pipe diameters,branch angles,seismic incident angles,and input ground motions.Moreover,an influence coefficient,which measures the influence of pipe connections on pipe JDs,is calculated.Results show that pipe connections can reduce the JDs of segmented pipes by 40%-50%.Furthermore,the JD is more sensitive to the connection shape,ground condition and pipe diameter than the incident angle and characteristics of seismic waves.An influence coefficient of 0.65 is recommended conservatively for the design of the buried segmented pipes.

Coexisting hidden attractors in a 4D segmented disc dynamo with one stable equilibrium or a line equilibrium

This paper introduces a four-dimensional （4D） segmented disc dynamo which possesses coexisting hidden attractors with one stable equilibrium or a line equilibrium when parameters vary. In addition, by choosing an appropriate bifurcation parameter, the paper proves that Hopf bifurcation and pitchfork bifurcation occur in the system. The ultimate bound is also estimated. Some numerical investigations are also exploited to demonstrate and visualize the corresponding theoretical results.

Study on the ignition process of a segmented plasma torch

Direct current plasma torches have been applied to generate unique sources of thermal energy in many industrial applications. Nevertheless, the successful ignition of a plasma torch is the key process to generate the unique source （plasma jet）. However, there has been tittle study on the underlying mechanism of this key process. A thorough understanding of the ignition process of a plasma torch will be helpful for optimizing the design of the plasma torch structure and selection of the ignition parameters to prolong the service life of the ignition module. Thus, in this paper, the ignition process of a segmented plasma torch （SPT） is theoretically and experimentally modeled and analyzed. Corresponding electrical models of different stages of the ignition process axe set up and used to derive the electrical parameters, e.g. the variations of the arc voltage and arc current between the cathode and anode. In addition, the experiments with different ignition parameters on a home-made SPT have been conducted. At the same time, the variations of the arc voltage and arc current have been measured, and used to verify the ones derived in theory and to determine the optimal ignition parameters for a particular SPT.

Multi-Objective Optimization of High Torque Density Segmented PM Consequent Pole Flux Switching Machine with Flux Bridge

Due to double salient structure,Flux Switching Machines(FSMs)are preferred for brushless AC high speed applications.Permanent Magnet(PM)FSMs(PM-FSMs)are suited applicants where high torque density(Tden)and power density(Pden)are the utmost requisite.However conventional PM-FSMs utilizes excessive rare earth PM volume VPM,higher cogging torque Tcog,high torque ripples(Trip)and comparatively lower(Tden)and Pden due to flux leakage.To overcome the aforesaid demerits,a new high(Tden)Segmented PM Consequent Pole(CP)FSM(SPMCPFSM)with flux bridge and barrier is proposed which successfully reduces VPM by 46.52%and PM cost by 46.48%.Moreover,Multi-Objective Optimization(MOO)examines electromagnetic performance due to variation in geometric parameters for global optimum parameters with key metric such as flux linkage(Φpp),flux harmonics(ΦTHD)average torque(Tavg),Tcog,Trip,Tden,average power(Pavg)and Pden.Analysis reveals that MOO improveΦpp by 22.68%,boost Tavg by 11.41%,enhanced Pavg by 4.55%and increased Tden and Pden by 11.41%.Detailed electromagnetic performance comparison with existing state of the art shows that proposed SPMCPFSM offer Tavg maximum up to 88.8%,truncate Trip up to 24.8%,suppress Tcog up to 22.74%,and results 2.45 times Tden and Pden.

Theoretical analysis of a new segmented anchoring style in weakly cemented soft surrounding rock

According to the tensile failure of rock bolt in weakly cemented soft rock, this paper presents a new segmented anchoring style in order to weaken the cumulative effect of anchoring force associated with the large deformation. Firstly, a segmented mechanical model was established in which free and anchoring section of rock bolt were respectively arranged in different deformation zones. Then, stress and displacement in elastic non-anchoring zone, elastic anchoring zone, elastic sticking zone, softening sticking zone and broken zone were derived respectively based on neural theory and tri-linear strain softening constitutive model of soft rock. Results show that the anchoring effect can be characterized by a supporting parameter b. With its increase, the peak value of tangential stress gradually moves to the roadway wall, and the radial stress significantly increases, which means the decrease of equivalent plastic zone and improvement of confining effect provided by anchorage body. When b increases to 0.72, the equivalent plastic zone disappears, and stresses tend to be the elastic solutions. In addition, the anchoring effect on the displacement of surrounding rock can be quantified by a normalization factor δ.

Segmented tubular synthesis of monodispersed microsized copper oxalate

Monodispersed microsized copper oxalate particles were prepared in a segmented continuous flow tube reactor, and the effect of the main parameters such as organic additive agent, initial copper ions concentration, residence time, and segmented media on the final products were investigated experimentally. The obtained copper oxalate microsized particles were disc-like in the presence of citrate ligand,which was the shape inducer for the precipitated copper oxalate. Thermodynamic equilibrium diagrams of the Cu(Ⅱ)-oxalate-H_2O,Cu(Ⅱ)-oxalate-citrate-H_2O, and Cu(Ⅱ)-oxalate-EDTA-H_2O solution systems were drawn to estimate the possible copper species under the experimental conditions and to explain the formation mechanisms of copper oxalate particles in the segmented fluidic reactor. Both theoretical and experimental results indicated that the presence of chelating reagents such as citrate and EDTA had distinct effect on the evolution of particle shape. Air and kerosene were tested as media for the fluidic flow segmentation, and the latter was verified to better promote the growth of copper oxalate particles. The present study provides an easy method to prepare monodispersed copper oxalate microsized particles in a continuous scaling-up way, which can be utilized to prepare the precursor material for conductive inks.

Plasma discharge characteristics of segmented diverter strips subject to lightning strike

In order to research segmented diverters for aircraft lightning protection, a transient 2 D multiphysics model based on magnetohydrodynamics theory is proposed to predict the location of the arc plasma discharge and lightning channel, and to simulate the electrothermal behavior.Based on numerical calculation and preliminary analysis, factors that affect the breakdown voltage of the segmented diverter are discussed. The results show that the voltage increase rate of the voltage source, the width of the air gap between metal segments and the geometry of these segments influence the breakdown voltage of the strip. High-voltage tests of the segmented diverter are performed to reveal air breakdown of the strip and redirect the lightning current.Experimental and numerical results are compared to verify the correctness of the numerical model. The ionization of the air gap between metal segments and the breakdown voltage of the strip calculated by the model are qualitatively consistent with experimental results. The breakdown voltage of the segmented diverter is far lower than the lightning voltage. When a lightning strike occurs, the segmented diverter can be quickly ionized to form a plasma channel which can guide the lightning current well.

Laboratory Research on Effective Test Area of Short-Crested Waves Generated by Two-Sided Segmented Wavemakers

The size and shape of the effective test area are crucial to consider when short-crested waves are created by segmented wavemakers. The range of the effective test area of short-crested waves simulated by two-sided segmented wavemakers is analyzed in this paper. The experimental investigation on the wave field distribution of short-crested waves generated by two-sided segmented wavemakers is conducted by using an array of wave gauges. Wave spectra and directional spreading function are analyzed and the results show that when the main direction is at a certain angle with the normal line of wave generators, the wave field of 3D short-crested waves generated by two-sided segmented wavemakers has good spatial uniformity within the model test area. The effective test area can provide good wave environments for seakeeping model tests of various ocean engineering structures in the deep ocean engineering basin.

SYNTHETIC STUDIES ON BLOOD COMPATIBLE BIOMATERIALS Ⅲ. SYNTHESIS, CHARAC-TERIZATION AND ANTITHROMBOGENICITY OF DIMETHYLDIPHEN YLPOLYSILOXANE/POLY (OXYTETRAM ETHYLENE)-POLYUREA SEGMENTED COPOLYMERS

A novel class of segmented copolymers, dimethyldiphenylpolysiloxane/poly (oxytetramethylene)-polyurea (PSPEU), was synthesized from α , ω-bis (γ-aminopropyl) dimethyldiphenylpolysiloxane (APMPS), which was prepared by means of basic ring-opening copolymerization of octamethylcyclotetrasiloxane, hexaphenylcyclotrisiloxane and 1, 3-bis (γ-aminopropyl) tetramethyl disiloxane. The relationships between the diphenylsiloxy contents and the properties of APMPS, including refractive index, glass transition temperature, solubility parameter as well as thermal stability, were investigated; meanwhile, the thermal stability, dynamic mechanical properties, mechanical properiesas well as the antithrombogenicity in vitro of the PSPEU were also revealed.

THERMALLY STIMULATED SHAPE MEMORY BEHAVIOR OF(ETHYLENE OXIDE-BUTYLENE TEREPHTHALATE)SEGMENTED COPOLYMER

The thermally stimulated shape memory behavior of ethylene oxide-butylene terephthalate (EOBT) segmented copolymers with different soft segment molecular weight and hard segment content was investigated. The deformation recovery ratio R-f of the EOBT samples increases with the soft segment molecular weight and the hard segment weight content, while the average overall deformation recovery speed V-r increases with the hard segment content. The temperature of maximum deformation recovery speed (T-M) is determined by the melting temperature of the soft segment crystals and the stability of the crystallized hard segment domains.

Segmented evolution of Deyang-Anyue erosion rift trough in Sichuan Basin and its significance for oil and gas exploration, SW China

Based on analysis of field survey, drilling and seismic data, the formation and evolution process of Deyang-Anyue erosion rift trough in Sichuan Basin was reconstructed, and exploration areas were divided and evaluated. The results show that:(1) Dengying Formation in and around Deyang-Anyue erosion rift trough varies widely in sedimentary characteristics. The Dengying Formation in the northern part of the erosion rift trough developed deep-water sediments, the Dengying Formation in the northern part of the basin varied gradually from basin to slope, platform margin, and restricted platform, and the Dengying Formation in the middle and southern parts of the trough developed carbonate platform facies.(2) Deyang-Anyue erosion rift trough is formed by extensional rift and karst erosion jointly, the north section of the erosion rift trough is mainly the product of tensile rift, while the middle and south sections are formed by erosion in multi-episodes of Tongwan period.(3) Based on the segmented origins of the erosion rift trough, Dengying Formation in and around it is divided into three exploration fields: lithologic mound and beach bodies at the northern platform margin of the basin, karst mound and beach bodies in the central platform, and karst residual mounds in the central southern trough of the basin, among them, the karst residual mounds in the central southern trough of the basin are a new frontier for natural gas exploration in the basin, and the lithologic mound and beach bodies at the northern platform margin are a new position for increasing the reserves of trillions of cubic meters of natural gas resources in the basin.