Analysis on Stability of Coning Motion of Rockets Based on Nutation Theory

A nonlinear mathematic model taking the nutation and precession angles as variables for the coning motion of projectile was established according to a short period moment projection of the spining projectile. By introducing the generalized nutation angle and precession angular speed, the model that is difficult to be resolved can be transformed to a resolvable one. The interrelationship between nutation and precession was analyzed based on the linear model, and the stability condition was obtained for the spinning projectile. For the nonlinear model, the effects of the nutation and precession on the limit circle of the projectile's coning motion were investigated, and the analytical relations between the nutation angle and the precession angular speed in the steady coning motion of the spinning projectile were given.

Implement of the Production Monitoring and Control System for Coning,Drawing and Twisting's Workshop

To achieve the production information management of the coning,drawing and twisting's workshop,and promote a good and fast development of the textile enterprise,firstly,we analyze the information technology development status of the textile enterprise at home and abroad,study the weaknesses of the existing computer monitoring system,introduce the system design project,and propose a system network model based on client/server(C/S)mode.Secondly,a multi-agent production monitoring and control system is developed,and the communication of the single-port-multi-protocol and a multi-thread data collection technology are studied via the multi-thread and standard template library(STL)technologies.Thirdly,the system management functions,the structure design of the database,and the technical difficulties in the process of software design are also introduced.As proved in practice,the system satisfies the production management requirements of the workshop,and implements the network management of the production information.

Coning motion stability of wrap around fin rockets

Both the asymptotical stability criterion and the bounded stability criterion of the coning motion for wrap around fin(WAF) rockets are proposed through the analy-sis of coning motion equations,which can be easily used to determine the exis-tence of the coning motion during the rocket design. The correctness of the crite-rions is verified by mathematical simulation examples of a WAF rocket with differ-ent setting angles. It is also found that the setting angle of WAF has great effects on the rolling moment and side moment of the rocket.

An experimental study on self-output-control characteristics of micro downwind rotor with coning soft blades

In this short paper,we have treated the aerodynamic performance of micro downwind rotor with coning soft blades experimentally.The test wind rotor has the tip diameter of 1.5 m and three two-dimensional NACA0018 blades of 0.15 m chord whose material is light,soft and pliable foam plastic for perfect safety.From the wind tunnel test,it is realized that the performance is manageable by the coning angle of the rotor blade.In the present case,an improvement of the performance in lower wind speeds is achieved by using the coning blade of 20°.Besides,owing to the torsional deformation of very soft blade,the self-power control characteristic is observed in every test rotor regardless of coning angle in the range of 0°-20° under the wind speed less than 12 m/s.

Coning motion instability of spinning missiles induced by the delay of strap-down seeker

The strap-down seeker,which combines the seeker's and the onboard gyro's measurements to obtain the target information,has been extensively applied by spinning missiles.The response delay of the strap-down seeker,a novel factor that could result in crosscoupling between the acceleration commands in the pitch and yaw channels and subsequently cause the significant deterioration in dynamic stability of the spinning missile equipped with a rate loop,is noted in this paper.The sufficient and necessary stability conditions are also analytically established based on the system equation with complex coefficient,which are further verified by numerical simulations.It could be indicated that the response delay of the strap-down seeker will greatly deteriorate the dynamic stability of the whole guidance system designed by the conventional method.It is also noticed from analysis that the stable region of the combined guidance coefficient is shrunken significantly with the increase of the spinning rate.

Effect of eccentric and inclined loading on the bearing capacity of strip footing placed on rock mass

This paper deals with the bearing capacity determination of strip footing on a rock mass in hilly area by considering the influence of inclined and eccentric loading. Applying the generalized HoekBrown failure criterion, the failure behavior of the rock mass is modeled with the help of the power cone programming in the lower bound finite element limit analysis framework. Using bearing capacity factor(Ns), the change in bearing capacity of the strip footing due to the occurrence of eccentrically inclined loading is presented. The variations of the magnitude of Ns are obtained by examining the effects of the Hoek-Brown rock mass strength parameters(uniaxial compressive strength(sci), disturbance factor(D), rock parameter(mi), and Geological Strength Index(GSI)) in the presence of different magnitudes of eccentricity(e) and inclination angle(λ) with respect to the vertical plane, and presented as design charts. Both the inclined loading modes, i.e., inclination towards the center of strip footing(+λ) and inclination away from the center of strip footing(-λ), are adopted to perform the investigation. In addition, the correlation between the input parameters and the corresponding output is developed by utilizing the artificial neural network(ANN). Additionally, from sensitivity analysis, it is observed that inclination angle(λ) is the most sensitive parameter. For practicing engineers, the obtained design equation and design charts can be beneficial to understand the bearing capacity variation in the existence of eccentrically inclined loading in mountain areas.

Three-Dimensional Conjugate Tooth Surface Design and Contact Analysis of Harmonic Drive with Double-Circular-Arc Tooth Profle

A three-dimensional conjugate tooth surface design method for Harmonic Drive with a double-circular-arc tooth profle is proposed. The radial deformation function of the fexspline (FS), obtained through Finite Element (FE) analysis, is incorporated into the kinematics model. By analyzing the FS tooth enveloping process, the optimization of the overlapping conjugate tooth profle is achieved. By utilizing the hobbing process, the three-dimensional machinable tooth surface of FS can be acquired. Utilizing the coning deformation of the FS, simulations are conducted to analyze the multi-section assembly and meshing motion of the machinable tooth surface. The FE method is utilized to analyze and compare the loaded contact characteristics. Results demonstrate that the proposed design method can achieve an internal gear pair consisting of a circular spline with a spur gear tooth surface and the FS with a machinable tooth surface. With the rated torque, approximately 24% of the FS teeth are engaged in meshing, and more than 4/5 of the tooth surface in the axial direction carries the load. The contact patterns, maximum contact pressure, and transmission error of the machinable tooth surface are 227.2%, 40.67%, and 71.24% of those on the spur gear tooth surface, respectively. It clearly demonstrates exceptional transmission performance.

数字经济时代财务人员财务舞弊行为影响因素的作用机理及治理

数字经济与传统财务工作的深度融合,强化了企业财务决策支持能力,提升了企业治理效率,但企业财务人员舞弊行为仍然层出不穷。为探索治理财务人员舞弊行为的有效途径,本文将行为经济学理论与GONE理论相结合,构建财务人员个体心理、群体心理、企业内部环境、企业外部环境四个影响因素对财务舞弊行为的诱导框架,解析数字经济时代财务人员的个性心理和群体心理,探讨企业内部环境和外部环境对财务人员财务舞弊行为的作用机理,并提出财务人员财务舞弊行为的治理对策。

A novel seed cone of Pinus from the Miocene of coastal Southeast China indicates kinship with Southeast Asian pines

Pinus is an economically and ecologically important genus whose members are dominant components globally in low-latitude mountainous and mid-latitude temperate forests.Pinus species richness is currently concentrated in subtropical mid-low latitudes of the Northern Hemisphere,differing from the latitudinal diversity gradient mostly recognized in woody angiosperms.How the present pattern was developing in Earth's past is still poorly studied,particularly in eastern Asia.Here,a new fossil species,Pinus shengxianica sp.nov.is described based on a fossil seed cone from the Late Miocene Shengxian Formation in Zhejiang,southeast China.A co-occurring cone is recognized as a known fossil species,Pinus speciosa Li.Extensive comparison of extant and fossil members of Pinus suggests P.shengxianica shares a striking cone similarity to Pinus merkusii and Pinus latteri(subsection Pinus)from tropical Southeast Asia in having annular bulges around the umbo on the apophysis.The morphological resemblance indicates these two extant low-latitude pines probably possess a close affinity with the present newly-discovered P.shengxianica and originated from East Asian mid-low latitude ancestors during this generic re-diversification in the Miocene.This scenario is consistent with the evolutionary trajectory reflected by the pine fossil history and molecular data,marking the Miocene as a key period for the origin and evolution of most extant pines globally.The co-occurrences of diverse conifers and broadleaved angiosperms preferring diverse niches demonstrate Late Miocene eastern Zhejiang was one of the hot spots for coniferophyte diversity and hosted a needled-broadleaved mixed forest with complex vegetation structure and an altitudinal zonation.

Design and Experimental Testing of an Electric Field-Driven Droplet Injection Device

The properties of droplets produced by existing on-demand injection systems are typically determined by the nozzle diameter,i.e.,only droplets with size larger than this diameter can be obtained.To solve this problem,a system for electricfield-driven droplet injection and deposition was developed,and the related performances were compared with those of a standard pneumatic system.The results show that the diameter of droplets gen-erated accordingly can be significantly smaller than the nozzle diameter.In particular,the effects of frequency and duty ratio on the number of droplets were studied by assuming microcrystalline wax as work material.A deposi-tion matrix was obtained by using a nozzle with a diameter of 200μm.The average diameter of the matrix was 80.17μm with a standard deviation of 2.65μm and the average spacing was 301.25μm with a standard deviation of 6.80μm.Four deposition states after droplet injection were considered and verified under different velocities of F60,F10,F3,and F0.We also provide an explanation for the existence of a series of inclined columns showing up during the deposition processs.

Transcriptome Analysis of Auxin Drives Cone Size Regulation in Fokienia hodginsii

As the reproductive organ of the endangered species Fokienia hodginsii,the size of the cones is a constraint on the reproductive renewal of the population.In this study,the molecular basis of the influence of cone size on F.hodginsii was elucidated by comparing the phenotype,biochemistry,and transcriptome of two cultivars of F.hodginsii(‘FJ431’and‘FJ415’).The two cultivars differed significantly in cone size,with FJ431 having a significantly larger cone size and weight than FJ415,1.32 and 1.90 times that of FJ415,respectively.RNA-Seq analysis of both cultivars retrieved 75,940 genes whose approximate functions were classified as the pathway of response to endogenous stimulus and response to hormone and showed significant differences in the auxin-activated signaling pathway,particularly the MAPK signaling pathway-plant.Furthermore,the endogenous IAA content was significantly higher in FJ431 than in FJ415,and 1.58 and 1.29 times more IAA was present in immature and mature cones,respectively.Moreover,exogenous IAA treatment significantly induced the expression of the MAPK pathway-related gene TRINITY_DN10564_c0_g1 and significantly inhibited the expression of the MAPK pathwayrelated gene TRINITY_DN17056_c0_g1.Our work suggests that IAA can affect the cone size of F.hodginsii,most probably through the MAPK pathway.This has high theoretical and practical significance for the improvement of genetic breeding and the further cultivation of quality germplasm resources of F.hodginsii.

Generalized Kannan-type contraction and fixed point theorems

In this paper,the generalized Kannan-type contraction in cone metric spaces over Banach algebras is introduced.The fixed point theorems satisfying generalized contractive conditions are obtained,without appealing to completeness of X or normality of the cone.The continuity of the mapping is relaxed.Furthermore,we prove that the completeness in cone metric spaces over Banach algebras is necessary if the generalized Kannan-type contraction has a fixed point in X.These results greatly generalize several well-known comparable results in the literature.

Strain localization of Mohr-Coulomb soils with non-associated plasticity based on micropolar continuum theory

To address the problems of strain localization, the exact Mohr-Coulomb (MC) model is used based on second-order cone programming (mpcFEM-SOCP) in the framework of micropolar continuum finite element method. Using the uniaxial compression test, we focused on the earth pressure problem of rigid wall segment involving non-associated plasticity. The numerical results reveal that when mpcFEM-SOCP is applied, the problems of mesh dependency can be effectively addressed. For geotechnical strain localization analysis involving non-associated MC plasticity, mpcFEM-SOCP in conjunction with the pseudo-time discrete scheme can improve the numerical stability and avoid the unreasonable softening issue in the pressure-displacement curves, which may be encountered in the conventional FEM. It also shows that the pressure-displacement responses calculated by mpcFEM-SOCP with the pseudo-time discrete scheme are higher than those calculated by mpcFEM-SOCP with the Davis scheme. The inclination angle of shear band predicted by mpcFEM-SOCP with the pseudo-time discrete scheme agrees well with the theoretical solution of non-associated MC plasticity.

Subaqueous volcanic eruptive facies,facies model and its reservoir significance in a continental lacustrine basin:A case from the Cretaceous in Chaganhua area of southern Songliao Basin,NE China

The conventional lithofacies and facies model of subaerial and marine pyroclastic rocks cannot reflect the characteristics of subaqueous volcanic edifice in lacustrine basins.In order to solve this problem,the lithofacies of subaqueous eruptive pyroclastic rocks is discussed and the facies model is established by taking the tuff cone of Cretaceous Huoshiling Formation in the Chaganhua area of the Changling fault depression,Songliao Basin as the research object.The results indicate that the subaqueous eruptive pyroclastic rocks in the Songliao Basin can be divided into two facies and four subfacies.The two facies are the subaqueous explosive facies and the volcanic sedimentary facies that is formed during the eruption interval.The subaqueous explosive facies can be further divided into three subfacies:gas-supported hot pyroclastic flow subfacies,water-laid density current subfacies and subaqueous fallout subfacies.The volcanic sedimentary facies consists of pyroclastic sedimentary rocks containing terrigenous clast subfacies.A typical facies model of the tuff cone that is formed by subaqueous eruptions in the Songliao Basin was established.The tuff cone is generally composed of multiple subaqueous eruption depositional units and can be divided into two facies associations:near-source facies association and far-source facies association.The complete vertical succession of one depositional unit of the near-source facies association is composed of pyroclastic sedimentary rocks containing terrigenous clast subfacies,gas-supported hot pyroclastic flow subfacies,water-laid density current subfacies and subaqueous fallout subfacies from bottom to top.The depositional unit of the far-source facies association is dominated by the subaqueous fallout subfacies and contains several thin interlayered deposits of the water-laid density current subfacies.The gas-supported hot pyroclastic flow subfacies and the pyroclastic sedimentary rocks containing terrigenous clast subfacies are favorable subaqueous eruptive facies for reservoirs in continental lacustrine basins.

Spray Characteristics of Non-Circular Nozzle in Air-Assisted Injection System

In order to analyze the spray characteristics of non-circular nozzle holes based on the air-assisted spray system, the spray characteristics of circular and non-circular nozzles were studied under the pressure of 0.2-0.6 MPa and the spray volume of 1000-5000 mL/h. Elliptical nozzle and triangular nozzle are classified as non-circular geometries. The spray cone angle was measured by processing the spray image captured by a CCD camera. The measured spray cone angles of the circular nozzles were analyzed, and the axis switching phenomenon of minor plane of elliptical nozzle was found during the test. Among the three shapes of nozzles, the elliptical nozzle had the largest spray cone angle, and the triangular nozzle had the smallest. The velocity field obtained depended on the PIV system. The results show that for axial velocity, elliptical orifice spray has greater kinetic energy and smaller droplet size under the same working parameters. Compared with the circular and elliptical nozzles, triangular orifice reached maximum spray velocity the fastest, but its velocity decay was the fastest. For radial velocity, away from the axis, the spray velocity of the elliptical orifice was less affected by the injection parameters, and the velocity was less than that of circular orifice and triangle orifice. Increasing air pressure will weaken radial propagation. The increase of liquid spraying rate had no remarkable effect on the increase of spraying rate. The results of particle size analysis show that the particle size of the non-circular orifice is reduced compared with that of the circular orifice, which promotes the breakup of droplets to a certain extent and enhances the atomization effect.

New clinical application of digital intraoral scanning technology in occlusal reconstruction:A case report

BACKGROUND Digital intraoral scanning,although developing rapidly,is rarely used in occlusal reconstruction.To compensate for the technical drawbacks of current occlusal reconstruction techniques,such as time consumption and high technical requirements,digital intraoral scanning can be used in clinics.This report aims to provide a way of selecting the most suitable maxillo-mandibular relationship(MMR)during recovery.CASE SUMMARY A 68-year-old man with severely worn posterior teeth underwent occlusal reconstruction with fixed prosthesis using digital intraoral scanning.A series of digital models in different stages of treatment were obtained,subsequently compared,and selected using digital intraoral scanning together with traditional measurements,such as cone beam computed tomography,joint imaging,and clinical examination.Using digital intraoral scanning,the MMR in different stages of treatment was accurately recorded,which provided feasibility for deciding the best occlusal reconstruction treatment,made the treatment process easier,and improved patient satisfaction.CONCLUSION This case report highlights the clarity,recordability,repeatability,and selectivity of digital intraoral scanning to replicate and transfer the MMR during occlusal reconstruction,expanding new perspectives for its design,fabrication,and postoperative evaluation.

An Alternative Way to Mapping Cone: The Algebraic Topology of the Pinched Tensor

In this research, we explore the properties and applications of the mapping cone and its variant, the pinched mapping cone. The mapping cone is a construction that arises naturally in algebraic topology and is used to study the homotopy type of spaces. It has several key properties, including its homotopy equivalence to the cofiber of a continuous map, and its ability to compute homotopy groups using the long exact sequence associated with the cofiber. We also provide an overview of the properties and applications of the mapping cone and the pinched mapping cone in algebraic topology. This work highlights the importance of these constructions in the study of homotopy theory and the calculation of homotopy groups. The study also points to the potential for further research in this area which includes the study of higher homotopy groups and the applications of these constructions to other areas of mathematics.

收益率椭球分布不确定下的均值-CVaR优化研究

The article explores a mean-CVaR ratio model with returns distribution uncertainty.To describe the uncertainty of returns distribution,a mixture ellipsoidal distribution absorbing some typical distributions such as the mixture distribution and and ellipsoidal distribution is introduced.Then,by using robust technique with some assumptions,the original robust mean-CVaR ratio model can be formulated as a second-order cone optimization model where the underlying random returns have a mixture ellipsoidal distribution.As an illustration,the corresponding robust optimization models are applied to allocations of assets in securities market.Numerical simulations are presented to illustrate the relation between robustness and optimality and to compare mixture ellipsoidal distribution to some typical distributions as well.

Methodology for Obtaining Optimal Sleeve Friction and Friction Ratio Estimates from CPT Data

Cone penetration testing (CPT) is a cost effective and popular tool for geotechnical site characterization. CPT consists of pushing at a constant rate an electronic penetrometer into penetrable soils and recording cone bearing (qc), sleeve friction (fc) and dynamic pore pressure (u) with depth. The measured qc, fs and u values are utilized to estimate soil type and associated soil properties. A popular method to estimate soil type from CPT measurements is the Soil Behavior Type (SBT) chart. The SBT plots cone resistance vs friction ratio, Rf [where: Rf = (fs/qc)100%]. There are distortions in the CPT measurements which can result in erroneous SBT plots. Cone bearing measurements at a specific depth are blurred or averaged due to qc values being strongly influenced by soils within 10 to 30 cone diameters from the cone tip. The qcHMM algorithm was developed to address the qc blurring/averaging limitation. This paper describes the distortions which occur when obtaining sleeve friction measurements which can in association with qc blurring result in significant errors in the calculated Rf values. This paper outlines a novel and highly effective algorithm for obtaining accurate sleeve friction and friction ratio estimates. The fc optimal filter estimation technique is referred to as the OSFE-IFM algorithm. The mathematical details of the OSFE-IFM algorithm are outlined in this paper along with the results from a challenging test bed simulation. The test bed simulation demonstrates that the OSFE-IFM algorithm derives accurate estimates of sleeve friction from measured values. Optimal estimates of cone bearing and sleeve friction result in accurate Rf values and subsequent accurate estimates of soil behavior type.

Technique for Estimating the Cone Bearing Smoothing Parameters

Cone penetration testing (CPT) is an extensively utilized and cost effective tool for geotechnical site characterization. CPT consists of pushing at a constant rate an electronic cone into penetrable soils and recording the resistance to the cone tip (qc value). The measured qc values (after correction for the pore water pressure) are utilized to estimate soil type and associated soil properties based predominantly on empirical correlations. The most common cone tips have associated areas of 10 cm2 and 15 cm2. Investigators also utilized significantly larger cone tips (33 cm2 and 40 cm2) so that gravelly soils can be penetrated. Small cone tips (2 cm2 and 5 cm2) are utilized for shallow soil investigations. The cone tip resistance measured at a particular depth is affected by the values above and below the depth of interest which results in a smoothing or blurring of the true bearing values. Extensive work has been carried out in mathematically modelling the smoothing function which results in the blurred cone bearing measurements. This paper outlines a technique which facilitates estimating the dominant parameters of the cone smoothing function from processing real cone bearing data sets. This cone calibration technique is referred to as the so-called CPSPE algorithm. The mathematical details of the CPSPE algorithm are outlined in this paper along with the results from a challenging test bed simulation.