Design and Analysis of Terminal Guidance Law for Kinetic Interceptors based on Pulse Engine

A new terminal guidance law is proposed based on a solid propellant pulse engine and an improved proportional navigation method to address the terminal guidance issue for kinetic interceptors.On this basis,the start-stop curve of the pulse motor during the terminal guidance process is designed,along with its start-up logic.The effectiveness of the proposed guidance strategy is verified through simulation.

A comparative study on the spectral characteristics of nanosecond pulsed discharges in atmospheric He and a He+2.3%H_(2)O mixture

Nanosecond pulsed discharges at atmospheric pressure in a pin-to-pin electrode configuration are well reproducible in time and space, which is beneficial to the fundamentals and applications of low-temperature plasmas. In this experiment, the discharges in helium(He) and He with 2.3%water vapor(H_(2)O) are driven by a series of 10 ns overvoltage pulses(~13 k V). Special attention is paid to the spectral characteristics obtained in the center of discharges by time-resolved optical emission spectroscopy. It is found that in helium, the emission of atomic and molecular helium during the afterglow is more intense than that in the active discharge, while in the He+2.3%H_(2)O mixture, helium emission is only observed during the discharge pulse and the molecular helium emission disappears. In addition, the emissions of OH(A-X) and Hα present similar behavior that increases sharply during the falling edge of the voltage pulse as the electrons cool down rapidly. The gas temperature is set to remain low at 540 K by fitting the OH(A-X) band. A comparative study on the emission of radiative species(He, He_(2), OH and H)is performed between these two discharge cases to derive their main production mechanisms. In both cases, the dominant primary ion is He^(+) at the onset of discharges, but their He^(+) charge transfer processes are quite different. Based on these experimental data and a qualitative discussion on the discharge kinetics, with regard to the present discharge conditions, it is shown that the electron-assisted three-body recombination processes appear to be the significant sources of radiative OH and H species in high-density plasmas.

Steady-state kinetics and osillation phenomena for complete oxidation of benzene over Pt/Al_2O_3 catalyst

The steady-state kinetics for complete oxidation of benzene over has been investigated by the external recycling reactor. The kinetics equation was described by the L-H model of adsorption of benzene and oxygen with the inhibition of carbon dioxide. The parameters of the kinetics model were estimated by the method of orthogonal design. The heats of adsorption of benzene, oxygen and carbon dioxide were determined by the method of gas-adsorption chromatography. The details of oscillations of complete oxidation of benzene were investigated.

Steady-state kinetics of <i>Roystonea regia</i>palm tree peroxidase

Royal palm tree peroxidase (RPTP) has been isolated to homogeneity from leaves of Roystonea regia palm trees. The enzyme purification steps included homogenization, (NH4)SO4 precipitation, extraction of palm leaf colored compounds and consecutive chromatography on Phenyl-Sepharose, TSK-Gel DEAE-5PW and Superdex-200. The novel peroxidase was characterized as having a molecular weight of 48.2 ± 3.0 kDa and an isoelectric point pI 5.4 ± 0.1. The enzyme forms dimers in solution with approximate molecular weight of 92 ± 2 kDa. Here we investigated the steady-state kinetic mechanism of the H2O2-supported oxidation of different organic substrates by RPTP. The results of the analysis of the initial rates vs. H2O2 and reducing substrate concentrations were seen to be consistent with a substrate-inhibited Ping-Pong Bi-Bi reaction mechanism. The phenomenological approach used expresses the peroxidase Ping-Pong mechanism in the form of the Michaelis-Menten equation and affords an interpretation of the effects in terms of the kinetic parameters KmH2O2, KmAH2, kcat, KSIH2O2, KSIAH2 and of the microscopic rate constants k1 and k3 of the shared three-step peroxidase catalytic cycle. Furthermore, the concentration and time-dependences and the mechanism of the suicide inactivation of RPTP by hydrogen peroxide were studied kinetically with guaiacol as co-substrate. The turnover number (r) of H2O2 required to complete the inactivation of the enzyme was 2154 ± 100 and the apparent rate constants of catalysis 185 s–1 and 18 s–1.

Simulation of the spatio-temporal evolution of the electron energy distribution function in a pulsed hollow-cathode discharge

This article presents the 2D simulation results of a nanosecond pulsed hollow cathode discharge obtained through a combination of fluid and kinetic models.The spatio-temporal evolution of the electron energy distribution function(EEDF)of the plasma column and electrical characteristics of the nanosecond pulsed hollow cathode discharge at a gas pressure of 5 Torr are studied.The results show that the discharge development starts with the formation of an ionization front at the anode surface.The ionization front splits into two parts in the cathode cavity while propagating along its lateral surfaces.The ionization front formation leads to an increase in the fast isotropic EEDF component at its front,as well as in the anisotropic EEDF component.The accelerated electrons enter the cathode cavity,which significantly contributes to the formation of the highenergy EEDF component and EEDF anisotropy.

Pulse-Width Pulse-Frequency Based Optimal Controller Design for Kinetic Kill Vehicle Attitude Tracking Control

The attitude control problem of the kinetic kill vehicle is studied in this work. A new mathematical model of the kinetic kill vehicle is proposed, the linear quadratic regulator technique is used to design the optimal attitude controller, and the pulse-width pulse-frequency modulator is used to shape the continuous control command to pulse or on-off signals to meet the requirements of the reaction thrusters. The methods to select the appropriate parameters of pulse-width pulse-frequency are presented in detail. Numerical simulations show that the performance of the LQR/PWPF approach can achieve good control performance such as pseudo-linear operation, high accuracy, and fast enough tracking speed.

Realization of proportional navigation and lateral acceleration autopilot for endoatmospheric kinetic interceptor with pulse thrusters

The guidance and control strategy for endoatmospheric kinetic interceptor controlled by lateral pulse thrusters was detailed.The pulse thruster control system was firstly proposed.The sample-and-hold approach was introduced to design a novel lateral acceleration autopilot on the basis of traditional two-loop topology.Combined with proportional navigation guidance law and the novel autopilot,the overall ballistic trajectory was presented and examined.Simulation results show that the pulse thruster control strategy can greatly improve the control system response speed and the maximal acceleration capability for realizing kinetic kill interception.

Kinetic analysis of soil contained pyrene oxidation by a pulsed discharge plasma process

A pulsed discharge plasma（PDP） reactor with net anode and net cathode was established for investigating the pyrene degradation in soil under different pulse peak voltage,air flow rate,pyrene content in soil,initial p H value and initial water content of the soil.Pyrene oxidation within the 60 min discharge time was fitting according to the pseudo-first order equation and the corresponding reaction kinetics constants（k values） were calculated.The obtained results show that pyrene oxidation under all the different reaction conditions obeyed the pseudo-first order equation well.Higher pulsed peak voltage and appropriate air flow rate were in favor of the increase of reaction rate of pyrene oxidation.A higher k value could be achieved in the lower initial pyrene content（the value was 100 mg kg^-1）.The k value of pyrene oxidation in the case of p H=4 was 11.2 times higher than the value obtained under the condition of p H=9,while the initial water content of the soil also has a large effect on the oxidation rate of pyrene due to the effect of PDP.

THE DISMUTATION OF SUPEROXIDE ANION BY COPPER(Ⅱ)COMPLEX OF 1,4,7,10-TETRAAZACYCLOTRIDECANE-11,13-DIONE—A KINETIC STUDY BY MEANS OF PULSE RADIOLYSIS

The dismutation kinetics of superoxide anion by copper complex of 1,4,7,10-tetranza- cyctotridecane-11,13-dione was studied by pulse radiolysis.The dismutation rate constants at various pH and concentration of complex were obtained.

Kinetic Monte Carlo simulation of growth of BaTiO_3 thin film via pulsed laser deposition

Considering the characteristics of perovskite structure, a kinetic Monte Carlo(KMC) model, in which Born-Mayer- Huggins(BMH) potential was introduced to calculate the interatomic interactions and the bonding ratio was defined to reflect the crystallinity, was developed to simulate the growth of BaTiO3 thin film via pulsed laser deposition(PLD). Not only the atoms deposition and adatoms diffusion, but also the bonding of adatoms were considered distinguishing with the traditional algorithm. The effects of substrate temperature, laser pulse repetition rate and incident kinetic energy on BaTiO3 thin film growth were investigated at submonolayer regime. The results show that the island density decreases and the bonding ratio increases with the increase of substrate temperature from 700 to 850 K. With the laser pulse repetition rate increasing, the island density decreases while the bonding ratio increases. With the incident kinetic energy increasing, the island density decreases except 6.2 eV<Ek<9.6 eV, and the bonding ratio increases at Ek<9.6 eV. The simulation results were discussed compared with the previous experimental results.

In-situ fabrication of particulate reinforced aluminum matrix composites under high-frequency pulsed electromagnetic field

Pulsed magnetic field is generated when imposing pulse signal on high-frequency magnetic field. Distribution of the inner magnetic intensity in induction coils tends to be uniform. Furthermore oscillation and disturbance phenomena appear in the melt. In. situ Al2O3 and Al3Zr particulate reinforced aluminum matrix composites have been synthesized by direct melt reaction using AlZr（CO3）2 components under a foreign field. The size of reinforced particulates is 2-3 μm. They are well distributed in the matrix. Thermodynamic and kinetic analysis show that high-frequency pulsed magnetic field accelerates heat and mass transfer processes and improves the kinetic condition of in-situ fabrication.

Simulation of multilayer Cu/Pd（100） heteroepitaxial growth by pulse laser deposition

The heteroepitaxial growth of multilayer Cu/Pd（100） thin film via pulse laser deposition （PLD） at room temperature is simulated by using kinetic Monte Carlo （KMC） method with realistic physical parameters. The effects of mass transport between interlayers, edge diffusion of adatoms along the islands and instantaneous deposition are considered in the simulation model, Emphasis is placed on revealing the details of multilayer Cu/Pd（100） thin film growth and estimating the Ehrlich-Schwoebel （ES） barrier. It is shown that the instantaneous deposition in the PLD growth gives rise to the layer-by-layer growth mode, persisting up to about 9 monolayers （ML） of Cu/Pd（100）. The ES barriers of 0.08 ± 0.01 eV is estimated by comparing the KMC simulation results with the real scanning tunnelling microscopy （STM） measurements,

Pulse radiolysis study on aqueous solution of nicotine

Nicotine has been studied for the first time by pulse radiolysis techniques. It has been found that hy- drated electrons, hydrogen radicals and hydroxyl radicals can react with nicotine to produce anion radicals and neu- tral radicals, respectively, and the related rate constants have been determined.

基于新型非线性函数的动能拦截器自抗扰姿态跟踪控制

针对动能拦截器在开展空间拦截任务时,对姿态控制系统快速性、准确性和鲁棒性的极高要求,提出了一种新型自抗扰控制方法.建立了动能拦截器姿态动力学模型,并将其转换为姿态跟踪误差二阶状态方程;基于自抗扰控制器中小误差大增益、大误差小增益的思想,设计了一种新型的非线性函数;基于该非线性函数,设计了一种新型的跟踪微分器,并且优化了扩张状态观测器和非线性控制器.将指定时间收敛的预设性能函数作为跟踪微分器的期望信号,可实现姿态误差按照预设性能函数收敛到期望值,且收敛时间可预先确定.利用伪速率(pseudo rate,PSR)脉冲调制器对连续控制力矩进行脉冲调制.数值仿真结果表明本文设计的控制方法具有较高的姿态控制精度,在面临环境扰动时具有较好的鲁棒性.

反射中子对金属快中子脉冲堆特性参数的影响研究

快中子脉冲堆对墙壁反射中子比较敏感,反射中子会改变快中子脉冲堆波形,当反射中子较多时可能会对脉冲堆的运行安全造成不利影响。本文建立了考虑墙壁反射中子效应的点堆动力学方法、蒙特卡罗中子学计算方法和ANSYS热力学计算方法三者耦合的“核-热-力”耦合方法,并对含有墙壁反射中子效应的快中子脉冲堆Godiva-Ⅰ瞬态过程进行分析。结果表明:反射中子使脉冲后沿提高,使冲坪时的反应性变低,使堆芯位移、应力有所提高。

改进型机-电模型及脉冲等离子体推力器能量转化效率分析

最初机-电模型是针对电磁轨道炮的电磁加速过程提出的,脉冲等离子体推力器(pulsed plasma thruster,PPT)的工作原理也是通过电磁加速产生元冲量,因此机-电模型是PPT能量转化及元冲量产生机制的主要理论分析工具之一.但是作为PPT放电回路一部分的等离子体通道,其几何形态与目前机-电模型的电流片模型存在明显差异.PPT放电通道在离开推进剂表面向外喷出过程中多呈现弯曲形状,并不断变化,而非平直片状.结合PPT放电通道的实际形态,本文提出了PPT放电通道的二维形态电流片模型,建立基于二维电流片的改进型机-电模型.通过分析放电通道受力情况以及电磁加速过程,推导了PPT羽流的电磁加速动能与放电回路电感量随时间演变函数的关系.针对机-电模型电路方程,提出了分段拟合PPT放电波形获得回路电感量随时间演变函数的算法.形成了基于PPT放电波形分析得到羽流电磁加速动能的计算方案.将改进型机-电模型应用于PPT样机能量转化效率评价,通过分析PPT放电能量转化过程阐释了PPT机-电转化效率低的原因,提出了提高PPT机-电效率的一种探索思路.

赋能动力学色谱法快速海水提铀研究

作为重要的分离和分析手段,液相色谱法主要应用在分析化学领域,而在核素分离工作中报道十分罕见。本项目基于动力学色谱理论基础,研发出一种脉冲式进样-赋能动力学色谱柱,色谱柱的填料采用粒径为0.2 mm的惰性二氧化硅,柱长为5 m,色谱分离单元约3.06万个。通过改变色谱柱外界条件,分析铀酰离子在色谱柱内的运动情况;通过水浴加热、超声波和外加磁场对色谱柱进行赋能,以提高离子相互分离的效果;在不同进样流速和温度下,研究混合核素的分离情况,得到最佳分离条件及色谱柱的动力学特性。结果表明,样品流速为4.109 mL·min^(−1),色谱柱加热温度为50℃,此时铀酰离子和钠离子的分离因数为1.1854。以最佳分离条件进行海水提铀,得到铀和钠离子的分离因数为α=1.575,实现海水中铀和钠离子分离理论上需要20级。脉冲式进样-赋能动力学色谱柱能够高效快速地实现海水中铀的分离提取。文中采用的创新性方法,还可应用于其他核素的分离研究。

Kinetic and binding equilibrium studies of dihydroflavonol 4-reductase from Vitis vinifera and its unusually strong substrate inhibition

Dihydroflavonol 4-reductase (DFR), a member of the short-chain dehydrogenase family, catalyzes the last common step in the biosynthesis of flavan-3-ols and condensed tannins. Initial rates of DFR were measured by monitoring the 340-nm absorbance decrease resulting from the joint consumption of dihydroquercetin (DHQ) and NADPH, as a function of pH, temperature and ionic strength. At pH 6.5 and 30o C, substrate inhibition was observed above 30 μM DHQ. At lower/non-inhibitory DHQ concentrations, NADP+ behaves as a competitive inhibitor with respect to NADPH and as a mixed inhibitor with respect to DHQ, which supports a sequential ordered mechanism, with NADPH binding first and NADP+ released last. Binding-equilib-rium data obtained by means of the chromatographic method of Hummel and Dreyer at pH 7.5 and by isothermal calorimetric titration at pH 6.5 led to the conclusion that ligands of the apoenzyme included NADPH, NADP+ and DHQ. The mechanism which best accounts for substrate inhibition at pH 6.5 in the absence of product involves the formation of a binary non-productive E.DHQ complex. Thus, a productive ternary complex cannot be formed when DHQ binds first. This mechanism of inhibition may prevent the accumulation of unstable leucoanthocyanidins within cells.

Effects of different pulsed vacuum drying strategies on drying kinetics,phenolic composition,and antioxidant capacity of chrysanthemum(Imperial chrysanthemum)

This work aimed to discuss effects of pulsed vacuum drying(PVD)at different temperatures(45°C,50°C,55°C and 60°C),vacuum durations(5 min,10 min and 15 min)and multi-stage heating on drying kinetics,colour attributes,phenolic compounds and antioxidant capacity of chrysanthemum(Imperial chrysanthemum).Results indicated that successive temperature increase reduced the drying time and enhanced the drying rate and moisture diffusivity.Lower temperature(45°C)and the multi-stage(35°C-55°C-60°C)drying presented the superiority in the protection of color,preservation of phytochemical composition(chlorogenic acid,luteolin,total phenolic and total flavonoid content)and improvement of antioxidant capacity(DPPH and FRAP)of chrysanthemum,which was attributed to the low-oxygen drying environment and reduction of thermal degradation losses.Based on the results of drying efficiency and drying quality,the multi-stage heating(35°C-55°C-60°C)has the excellent potential to produce high-quality dried chrysanthemum on a commercial scale.

低功率融合波铥激光前列腺剜切术对良性前列腺增生患者性功能的影响

目的:探讨应用新型低功率融合波铥激光行经尿道前列腺剜切术对良性前列腺增生(BPH)患者性功能的影响。方法:选取2022年1月至2023年6月江苏大学附属金坛医院泌尿外科收治的BPH患者89例,随机分为低功率融合波铥激光行经尿道前列腺剜切(LP-ThuVEP)组45例和经尿道前列腺等离子切除(TUPKRP)组44例,记录围手术期指标,对比分析两组患者术前和术后3、6个月IPSS、Qmax、Qavg、PVR、QoL,通过国际勃起功能指数评分问卷表5(IIEF-5)和男性性健康调查问卷-射精功能障碍评分(MSHQ-EjD)评价手术对男性性功能的影响。结果:与TUPKRP组比较,LP-ThuVEP组在手术时间上差异无统计学意义(P>0.05),在膀胱冲洗时间、留置尿管时间、手术日血红蛋白下降幅度、术后排便诱发肉眼血尿消失时间方面,有显著差异(P<0.05或P<0.01)。两组围手术期并发症相当。排尿状况指标中,LP-ThuVEP组术后3个月IPSS、QoL评分和PVR较TUPKRP组有统计学差异(P<0.05);在男性性功能方面,IIEF-5评分在术后3个月及术后6个月两组间比较均有统计学差异(P<0.05);除了术后3个月组间射精相关满意度评分无统计学差异(P>0.05)之外,其他的组间及组内的术后3个月和术后6个月射精功能及满意度评分均有显著差异(P<0.01)。结论:较之TUPKRP,LP-ThuVEP同样可以高效解除BPH导致的尿路梗阻,且具有损伤更小、患者勃起功能和射精功能恢复更快等优势。