Partially-Observed Maximum Principle for Backward Stochastic Differential Delay Equations

Dear Editor,This letter investigates a partially-observed optimal control problem for backward stochastic differential delay equations(BSDDEs).By utilizing Girsanov’s theory and convex variational method,we obtain a maximum principle on the assumption that the state equation contains time delay and the control domain is convex.The adjoint processes can be represented as the solutions of certain time-advanced stochastic differential equations in finite-dimensional spaces.Linear backward stochastic differential equation(BSDE)was first introduced by Bismut in[1],while general BSDE was given by Pardoux and Peng[2].Since then,the theory of BSDEs developed rapidly.The corresponding optimal control problems,whose states are driven by BSDEs,have also been widely studied by some authors,see[3]-[5].

A compact X-band backward traveling-wave accelerating structure

Very high-energy electrons(VHEEs)are potential candidates for FLASH radiotherapy for deep-seated tumors.We proposed a compact VHEE facility based on an X-band high-gradient high-power technique.In this study,we investigated and realized the first X-band backward traveling-wave(BTW)accelerating structure as the buncher for a VHEE facility.A method for calculating the parameters of single cell from the field distribution was introduced to simplify the design of the BTW structure.Time-domain circuit equations were applied to calculate the transient beam parameters of the buncher in the unsteady state.A prototype of the BTW structure with a thermionic cathode-diode electron gun was designed,fabricated,and tested at high power at the Tsinghua X-band high-power test stand.The structure successfully operated with 5-MW microwave pulses from the pulse compressor and outputted electron bunches with an energy of 8 MeV and a pulsed current of 108 mA.

Dielectric Resonator Magnetoelectric Dipole Arrays with Low Cross Polarization,Backward Radiation,and Mutual Coupling for MIMO Base Station Applications

Dielectric resonator magnetoelectric dipole(DRMED)arrays with enhanced isolation,reduced cross-polarization,and backward radiation are proposed for base station(BS)applications.The proposed antenna comprises an elevated dielectric resonator antenna(DRA)on a small metal plate above a sizeable common ground plane.The DRA is designed in its T Eδ11 mode,acting like a magnetic dipole.The surface current excited by the differential probes flowing on the small ground plane is equivalent to an electric dipole.Since these two equivalent dipoles are orthogonal,they have the magnetoelectric dipole characteristics with reduced backward radiation.Meanwhile,the small ground planes can be treated as decoupling structures to provide a neutralization path to cancel the original coupling path.A linearly-polarized 4-element prototype array was verified experimentally in previous work.Here,a dual-polarized DRMED antenna is presented to construct a 2-element and 4×4 array for BS applications.To investigate its MIMO performance,sophisticated multi-cell scenario simulations are carried out.By using the proposed dualpolarized DRMED array,the cellular system capacityis improved by 118.6%compared to a conventional DRA array.This significant MIMO system improvement is mainly due to the reduced backward radiation and,therefore,reduced inter-cell interferences.Measurements align well with the simulations.

Accuracy of optimized Sirius ray-tracing method in intraocular lens power calculation

AIM:To evaluate the accuracy and predictability of ray tracing-assisted intraocular lens(IOL) calculation function in Sirius internal software and further improve the accuracy by optimizing the calculation of predicted lens position(PLP).METHODS:This retrospective study recruited 52 eyes of 49 patients.All of the cases with cataract had undergone phacoemulsification combined with IOL implantation.SRK-T,Haigis formula,and Sirius ray-tracing method were all used for each eye’s IOL calculation.The mean absolute value of prediction error(prediction error=predicted refraction-postoperative refraction) was defined as mean absolute prediction error(MAPE) and was determined for each method.Calculation of PLP was optimized by effective lens position(ELP).Optimized PLP was entered to Sirius internal software again to verify whether the method was improved.RESULTS:Compared with SRK-T and Haigis formulas,less accuracy was shown in Sirius ray-tracing method(P=0.001).The ELP of the IOL moved forward compared to PLP(P<0.001).The MAPE of the ELP-inputted Sirius ray-tracing method was reduced.ELP and PLP were well correlated.Taking ELP as y and PLP given by Sirius soft as x,a linear regression formula y=0.1637 x+3.1741 was concluded(R^(2)=0.1066,P=0.018).It was shown that the optimized Sirius ray-tracing method(optimized PLP entered),compared with SRK-T and Haigis formulas,worked with the same accuracy(P=0.038).CONCLUSION:The original Sirius ray tracing method is not satisfactory enough.However,in normal eyes,the optimized Sirius ray-tracing method in IOL calculation was as accurate as SRK-T and Haigis formulas.

Transition from backward to sideward stimulated Raman scattering with broadband lasers in plasmas

Broadband lasers have been proposed as future drivers of inertial confined fusion(ICF)to enhance the laser-target coupling efficiency via the mitigation of various parametric instabilities.The physical mechanisms involved have been explored recently,but are not yet fully understood.Here,stimulated Raman scattering(SRS)as one of the key parametric instabilities is investigated theoretically and numerically for a broadband laser propagating in homogeneous plasma in multidimensional geometry.The linear SRS growth rate is derived as a function of scattering angles for two monochromatic laser beams with a fixed frequency differenceδω.Ifδω/ω_(0)∼1%,withω0 the laser frequency,these two laser beams may be decoupled in stimulating backward SRS while remaining coupled for sideward SRS at the laser intensities typical for ICF.Consequently,side-scattering may dominate over backward SRS for two-color laser light.This finding of SRS transition from backward to sideward SRS is then generalized for a broadband laser with a few-percent bandwidth.Particle-in-cell simulations demonstrate that with increasing laser bandwidth,the sideward SRS gradually becomes dominant over the backward SRS.Since sideward SRS is very efficient in producing harmful hot electrons,attention needs to be paid on this effect if ultra-broadband lasers are considered as next-generation ICF drivers.

GENERAL COUPLED MEAN-FIELD REFLECTED FORWARD-BACKWARD STOCHASTIC DIFFERENTIAL EQUATIONS

In this paper we consider general coupled mean-field reflected forward-backward stochastic differential equations(FBSDEs),whose coefficients not only depend on the solution but also on the law of the solution.The first part of the paper is devoted to the existence and the uniqueness of solutions for such general mean-field reflected backward stochastic differential equations(BSDEs)under Lipschitz conditions,and for the one-dimensional case a comparison theorem is studied.With the help of this comparison result,we prove the existence of the solution for our mean-field reflected forward-backward stochastic differential equation under continuity assumptions.It should be mentioned that,under appropriate assumptions,we prove the uniqueness of this solution as well as that of a comparison theorem for mean-field reflected FBSDEs in a non-trivial manner.

Backward Support Computation Method for Positive and Negative Frequent Itemset Mining

Association rules mining is a major data mining field that leads to discovery of associations and correlations among items in today’s big data environment. The conventional association rule mining focuses mainly on positive itemsets generated from frequently occurring itemsets (PFIS). However, there has been a significant study focused on infrequent itemsets with utilization of negative association rules to mine interesting frequent itemsets (NFIS) from transactions. In this work, we propose an efficient backward calculating negative frequent itemset algorithm namely EBC-NFIS for computing backward supports that can extract both positive and negative frequent itemsets synchronously from dataset. EBC-NFIS algorithm is based on popular e-NFIS algorithm that computes supports of negative itemsets from the supports of positive itemsets. The proposed algorithm makes use of previously computed supports from memory to minimize the computation time. In addition, association rules, i.e. positive and negative association rules (PNARs) are generated from discovered frequent itemsets using EBC-NFIS algorithm. The efficiency of the proposed algorithm is verified by several experiments and comparing results with e-NFIS algorithm. The experimental results confirm that the proposed algorithm successfully discovers NFIS and PNARs and runs significantly faster than conventional e-NFIS algorithm.

Evaluation of corneal backward light scattering in type 2 diabetes mellitus

AIM:To compare the corneal backward light scattering values in type 2 diabetes mellitus(DM)patients with those of age and sex-matched healthy controls.METHODS:The study included 30 patients(30 eyes)with type 2 DM and 30 control subjects(30 eyes).Duration of diabetes,most recent hemoglobin A1c levels,along with the status of diabetic retinopathy,and existing medical treatment of all subjects were recorded.All subjects underwent a complete ophthalmologic examination.In addition,backward light scattering(densitometry)was measured to assess changes in corneal transparency using tomography(Pentacam HR).RESULTS:The type 2 DM patients included 12 males and 18 females and control subjects included 16 males and 14 females.The age was 50.40±7.80y(range:40-68y)of the diabetic group and 49.30±9.50y(rang:40-73y)of control group.The diabetic group demonstrated significantly higher mean densitometry values of the anterior(6-10 mm)zone(P=0.047),the total anterior layer(P=0.036)and the total cornea(P=0.043)than control group.The corneal densitometry of the diabetic eyes demonstrated no significant correlation with hemoglobin A1c levels and DM duration.CONCLUSION:Diabetic group has higher densitometry in anterior corneal(6-10 mm)zone,total anterior cornea,and total cornea and with no correlation with hemoglobin A1c levels and DM duration.

ANTICIPATED BACKWARD STOCHASTIC VOLTERRA INTEGRAL EQUATIONS WITH JUMPS AND APPLICATIONS TO DYNAMIC RISK MEASURES

In this paper, we focus on anticipated backward stochastic Volterra integral equations(ABSVIEs) with jumps. We solve the problem of the well-posedness of so-called M-solutions to this class of equation, and analytically derive a comparison theorem for them and for the continuous equilibrium consumption process. These continuous equilibrium consumption processes can be described by the solutions to this class of ABSVIE with jumps.Motivated by this, a class of dynamic risk measures induced by ABSVIEs with jumps are discussed.

THE REGULARIZED SOLUTION APPROXIMATION OF FORWARD/BACKWARD PROBLEMS FOR A FRACTIONAL PSEUDO-PARABOLIC EQUATION WITH RANDOM NOISE

This paper deals with the forward and backward problems for the nonlinear fractional pseudo-parabolic equation ut+(-Δ)^(s1)ut+β(-Δ)^(s2)u=F(u,x,t)subject o random Gaussian white noise for initial and final data.Under the suitable assumptions s1,s2andβ,we first show the ill-posedness of mild solutions for forward and backward problems in the sense of Hadamard,which are mainly driven by random noise.Moreover,we propose the Fourier truncation method for stabilizing the above ill-posed problems.We derive an error estimate between the exact solution and its regularized solution in an E‖·‖Hs22norm,and give some numerical examples illustrating the effect of above method.

Microstructure Distribution Characteristics of High-Strength Aluminum Alloy Thin-Walled Tubes during Multi-Passes Hot Power Backward Spinning Process

The microstructure of the thin-walled tubes with high-strength aluminum alloy determines their final forming quality and performance. This type of tube can be manufactured by multi-pass hot power backward spinning process as it can eliminate casting defects, refine microstructure and improve the plasticity of the tube. To analyze the microstructure distribution characteristics of the tube during the spinning process, a 3D coupled thermo-mechanical FE model coupled with the microstructure evolution model of the process was established under the ABAQUS environment. The microstructure evolution characteristics and laws of the tube for the whole spinning process were analyzed. The results show that the dynamic recrystallization is mainly produced in the spinning deformation zone and root area of the tube. In the first pass, the dynamic recrystallization phenomenon is not obvious in the tube. With the pass increasing, the trend of dynamic recrystallization volume percentage gradually increases and extends from the outer surface of the tube to the inner surface. The fine-grained area shows the states of concentration, dispersion, and re-concentration as the pass number increases. .

Glass-compatible and self-powered temperature alarm system by temperature-responsive organic manganese halides via backward energy transfer process

A pioneering glass-compatible transparent temperature alarm system self-powered by luminescent solar concentrators(LSCs) is reported.Single green-emitted organic manganese halides(OMHs) of PEA_(2)MnBr_(2)I_(2),which has a unique temperature-dependent backward energy transfer process from selftrapped state to^(4)T_(1)energy level of Mn,is used for triggering the temperature alarm.The LSC with redemitted CsPbI_(3)perovskite-polymer composite films on the glass substrate is used for power supply.The spectrally separated nature between the green-emitted OMHs for temperature alarm and red-emitted CsPbI3in LSC for power supply allows for probing the signal light of temperature-responsive OMHs without the interference of LSCs,making it possible to calibrate the temperature visually just by a self-powered brightness detection circuit with LED indicators.Taking advantage of LSC without hot spot effects plaguing the solar cells,as-prepared temperature alarm system can operate well on both sunny and cloudy day.

车联网中基于三方Stackelberg博弈的动态多媒体定价方案

在当前车联网的应用场景下,中继车辆数据转发的积极性低下与存储空间有限,导致用户体验质量(QoE)降低,为此提出基于三方Stackelberg博弈的动态多媒体定价方案.为了激励中继车辆参与转发多媒体内容,提出多媒体内容定价框架,其中中继车辆获得全额佣金后向路侧单元(RSU)支付部分佣金.设计基于Stackelberg博弈的动态定价模型,根据中继车辆、用户车辆与RSU三方的存储空间利用率、内容数据大小和成本因素,建立各自的效用函数,并将其转化为三方四阶段Stackelberg定价模型.通过反向归纳法证明纳什均衡的存在,实现三方之间的动态定价以得到各自最优策略.仿真结果表明,所提方案有效解决了中继车辆存储空间过载问题,并提高了中继车辆积极性,且在提升用户QoE方面较传统方案具有优势.

丹江口水库淅川库区大气硝酸盐干沉降特征及源解析

以丹江口水库淅川库区为研究区,于2021年1~12月设置5个监测点进行干沉降样品采集,分析了样品中硝酸盐浓度、通量及其氮氧同位素,基于稳定同位素模型(SIAR)量化了硝酸盐的主要来源.结果表明,库区干沉降中硝酸盐月均浓度为0.16mg/L,全年硝酸盐干沉降通量为2.49kg/(hm^(2)·a),δ15N-NO_(3)^(-)和δ^(18)O-NO_(3)^(-)月均值分别为(+0.17±4.10)‰、(+56.6±9.18)‰.干沉降中硝酸盐浓度、沉降通量和氮氧同位素的季节性差异显著,秋冬季节的硝酸盐浓度和沉降通量均高于春夏季节,主要与寒冷季节化石源排放量增加、大气边界层稳定性增强以及气粒转化平衡趋于颗粒态硝酸盐生成有关;冬季最高的δ15N-NO_(3)^(-)与冬季燃煤取暖和低温导致的氮同位素平衡分馏效应增加有关,夏季最低的δ^(18)O-NO_(3)^(-)则与NO_(2)+·OH途径形成硝酸盐占主导有关.SIAR分析结果发现,库区干沉降中硝酸盐主要来自化石源(交通排放及煤燃烧),贡献率为69.3%,其中交通排放源和煤燃烧源贡献率分别为51.1%和18.2%.冬季化石源的贡献率最高(72.0%),其中70.4%来源于交通排放.进一步证实交通排放和冬季燃煤取暖是影响库区干沉降中硝酸盐的主要因素,控制交通移动源污染排放和煤燃烧是今后减少大气中硝酸盐的重要举措.此外,较为稳定的生物质燃烧源对硝酸盐的贡献率表明外源输入也是库区硝酸盐干沉降中的重要来源.

一种基于SHVE的连接查询动态对称可搜索加密方案

对称可搜索加密(searchable symmetric encryption,SSE)因其较高的搜索效率得到了人们的广泛关注.支持连接查询的对称可搜索加密方案可以提高方案的功能性.然而现有大部分连接查询方案不支持对加密数据库的动态更新操作,结合静态对称隐藏向量加密(symmetric hidden vectors encryption,SHVE)的定义,提出支持动态数据更新的动态对称隐藏向量加密(dynamic SHVE,DSHVE)的定义,并在此定义下构造了一种适用于可搜索加密应用场景的DSHVE方案.在此基础上,通过引入基于盲指数计算的不经意动态交叉标签,设计具有前向和后向隐私的向量数据存取结构,构造了支持连接查询的动态对称可搜索加密方案,给出了方案的详细工作过程和正式的安全性分析.理论分析和实验结果表明,连接查询时,该方案能够在不明显增加存储和计算开销的前提下,有效避免泄露匹配文档索引之外的结果特征.同时该方案能够仅通过单轮通信实现连接查询,具有较低的通信开销和较高的搜索效率.

基于格密码的5G-R车地认证密钥协商方案

5G-R作为我国下一代高速铁路无线通信系统,其安全性对于保障行车安全至关重要。针对5G-AKA协议存在隐私泄露、根密钥不变和效率低等问题,基于格密码理论提出一种新型5G-R车地认证方案。首先,使用临时身份信息GUTI代替SUCI,克服了SUCI明文传输的缺点。其次,设计基于格密码的根密钥更新策略,采用格上公钥密码体制、近似平滑投射散列函数和密钥共识算法,实现了根密钥的动态更新和前后向安全性。再次,加入随机质询和消息认证码,实现了通信三方的相互认证,可有效防范重放、DoS等多种恶意攻击。最后,采用串空间形式化方法进行安全验证,结果表明:本文方法较其他方法有更高的安全性,被攻击成功的概率最低,仅为O(n^(2))×2^(-128),且有较低的计算开销和通信开销,能够满足5G-R高安全性的需求。

“金课”视域下“影视音乐”课程的混合式教学探索

“金课”的“两性一度”成为当前高校教学改革的目标之一。“影视音乐”课程存在教学理念滞后、教学形式与学生需求脱节等问题,基于此提出“金课”目标下,“影视音乐”课程混合式教学设计要增强学习的合作性和探究性、注重教学资源的创新性、融入人文性与思政性等策略,同时将逆向教学设计理论引入混合式教学中,提出影视音乐课程的教学设计框架。

一种求解包含问题的算法研究

一种实希尔伯特空间中求解包含问题的算法被提出,所提出的算法基于向前向后方法、压缩方法、惯性方法和无需搜索的自适应步长。算法的特点为迭代中多次使用惯性加速方法,且自适应步长随着迭代次数增加可能增大。在包含问题解集非空、一个映射极大单调、另一个映射单调且利普希茨连续的假设下,算法的强收敛性被证明。

分布式电源对配电网潮流计算的影响研究

配电中接入的分布式电源的增多,潮流计算时,传统的前推回代法无法满足精度要求。对系统研究发现,分布式电源的出力和接入位置对配电网的网损有不同的影响,阐述了分布式电源潮流计算模型,并引入了一种带有PV节点无功修正的分布式电源配电网潮流计算方法。通过对IEEE14节点系统进行仿真验证,证明了所提算法的有效性和收敛性。研究结果显示:新提出的方案和技术能够更加高效地解决带有分布式电源的配电网潮流问题。

指向深度学习的高中物理循证教学探索

循证教学是一种基于证据、培养批判性思维的教学模式,具有系统性与结构性、实践性与持续性、开放性与生成性的特征.证据收集、问题解决和反思评价是循证教学的核心,通过感知与体验、探究与反思、引发与维持的过程促进经验概念化、概念结构化和结构系统化.基于教学目标明确证据收集的维度、基于问题解决确定证据背后的原因、基于迁移应用实现概念结构的迭代和基于反思内化促进深度学习的发生是循证教学的有效策略.