摘要：Restricted genetic diversity can supply only a limited number of elite genes for modern plant cultivation and *** this study,we demonstrate that rational design enables the engineering of geranyl-geranyl diphosphate synthase(NtGGPPS),an enzyme of the methylerythritol phosphate pathway(MEP)in the model plant Nicotiana *** the crucial bottleneck in carotenoid biosynthesis,NtGGPPS1 interacts with phytoene synthase(NtPSY1)to channel GGPP into the production of *** of this enzyme in the ntggpps1 mutant leads to decreased carotenoid *** the aim of enhanc-ing NtGGPPS1 activity,we undertook structure-guided rational redesign of its substrate binding pocket in combination with sequence *** activity of the designed NtGGPPS1(a pentuple mutant of five sites V154A/I161L/F218Y/I209S/V233E,d-NtGGPPS1)was measured by a high-throughput colorimetric assay.d-NtGGPPS1 exhibited significantly higher conversion of IPP and each co-substrate(DMAPP~1995.5-fold,GPP~25.9-fold,and FPP~16.7-fold)for GGPP synthesis compared with wild-type ***,the transient and stable expression of d-NtGGPPS1 in the ntggpps1 mutant increased carotenoid levels in leaves,improved photosynthetic efficiency,and increased biomass relative to *** findings provide a firm basis for the engineering of GGPPS and will facilitate the development of quality and yield *** results open the door for the structure-guided rational design of elite genes in higher plants。

摘要：RF deflecting cavity can be used for bunch length measurement and is designed to diagnose the beam produced by the photocathode electron gun which was built at Tsinghua University for the Thomson scattering experiment. Detailed discussion and calculation for measuring the 3.5 MeV bunch and another with further acceleration to 50 MeV, which is under development, are presented. A standing-wave deflecting cavity working at 2856 MHz is designed and the power feeding system has been planned.

摘要：An optimization method for 3D blade and meridional contour of centrifugal or mixed-flow impeller based on the 3D viscous computational fluid dynamics （CFD） analysis is proposed. The blade is indirectly parameterized using the angular momentum and calculated by inverse design method. The design variables are separated into two categories： the meridional contour design vari- ables and the blade design variables. Firstly, only the blade is optimized using genetic algorithm with the meridional contour remained constant. The artificial neural network （ANN） techniques with the training sample data schemed according to design of experiment theory are adopted to construct the response relation between the blade design variables and the impeller performance. Then, based on the ANN approximated relation between the meridional contour design variables and impeller per- formance, the meridional contour is optimized. Fewer design variables and less calculation effort is required in this method that may be widely used in the optimization of three-dimension impellers. An optimized impeller in a mixed-flow pump, where the head and the efficiency are enhanced by 12.9% and 4.5% respectively, confirms the validity of this newly proposed method.

摘要：The martensitic transformation temperature is the basis for the application of shape memory alloys(SMAs),and the ability to quickly and accurately predict the transformation temperature of SMAs has very important practical *** this work,machine learning(ML)methods were utilized to accelerate the search for shape memory alloys with targeted properties(phase transition temperature).A group of component data was selected to design shape memory alloys using reverse design method from numerous unexplored *** modeling and feature modeling were used to predict the phase transition temperature of the shape memory *** experimental results of the shape memory alloys were obtained to verify the effectiveness of the support vector regression(SVR)*** results show that the machine learning model can obtain target materials more efficiently and pertinently,and realize the accurate and rapid design of shape memory alloys with specific target phase transition *** this basis,the relationship between phase transition temperature and material descriptors is analyzed,and it is proved that the key factors affecting the phase transition temperature of shape memory alloys are based on the strength of the bond energy between *** work provides new ideas for the controllable design and performance optimization of Cu-based shape memory alloys.

摘要：In this paper, we study the thermodynamic geometry for the charged Ad S black hole surrounded by quintessence. Three different kinds of the geometries are constructed, and the corresponding curvatures are obtained. It is found that there are different divergence behaviors of these curvatures, which is general thought to closely link to the phase transition of the black hole.

摘要：Distributed dynamic absorbers have many advantages such as wide frequency bandwidth for vibration suppression,strong detuning adaptability,and high system stability,making them very suitable for the vibration and noise control of continuous ***,they have broad application prospects in various fields such as transportation,aviation,and ***,there are still many challenges in the engineering applications of distributed dynamic absorbers for vibration suppression,including the engineering realization of the optimal damping of traditional optimal coherence dynamic absorbers,and the engineering applicability of the finite periodic array dynamic *** on the damping material properties obtained by the dynamic mechanical analyzer tests,this paper establishes the finite element model of the cantilever-beam-type dynamic absorber with constrained damping layers,aiming to realize the accurate determination of the optimal *** are conducted by attaching the traditional dynamic absorbers with the optimal damping to a thin-walled panel with four clamped *** show that the vibration of the panel is well suppressed,with the reduction of the frequency response peak larger than 14 dB and the reduction ratio of RMS larger than 58%within 500 ***,the periodically arrayed dynamic absorbers are designed according to the bandgap regulation *** tuning behavior of the arrayed dynamic absorbers by changing designing parameters is *** vibration reduction effect of arrayed dynamic absorbers is compared with that of the traditional dynamic absorbers under the same mass ratio through *** indicate that the arrayed dynamic absorbers are easier to design,and have a similar reduction effect on the modal vibration of the thin panel as the traditional dynamic absorbers within a narrow frequency range near the natural frequency,while they perform unsatisfactory in a broad ***,if t

摘要：This paper discusses the model-based predictive controller design of networked nonlinear systems with communica- tion delay and data loss. Based on the analysis of the closed-loop networked predictive control systems, the model-based networked predictive control strategy can compensate for communication delay and data loss in an active way. The designed model-based predictive controller can also guarantee the stability of the closed-loop networked system. The simulation re- suits demonstrate the feasibility and efficacy of the proposed model-based predictive controller design scheme.

摘要：We study the reflection of a straight line or a billiard on a plane in an n-dimensional Minkowski space. It is found that the reflection law coincides with that defined with respect to confocal quadratic surfaces in projective geometry. We then establish the full Poncelet theorem which holds in projective geometry in n-dimensional Minkowski space and in their quadratic surfaces including de Sitter and AdS spaces.

摘要：Traditional parafoil homing usually uses a point as object. As the mobility of parafoil is limited by its glide ratio and wind, in some cases when the parafoil scatter area is large, or the glide ratio of parafoil is small, the deviation of its landing point to object point will be arduous to control. Accordingly, during these situations, when parafoil is used in recovery of spacecraft or satellite, the landing area of parafoil can be set as a rectangle, and the object of parafoil can be set as a line segment. The thesis of this work is designing an algorithm for parafoil homing using line segment as object. The algorithm of wind velocity and direction calculation in different flying segments was also investigated. The algorithm designed navigates the parafoil to land into the predestined area and largely reduce the probability of recovery loads falling to unwanted area to damage houses and people.

摘要：With a triple-apex tip, we investigate theoretically the vertical manipulation of single Pt adatom on the Pt（111） surface. The adatom adsorbed on the f cc site of the flat Pt（111） surface can be transferred vertically to the tip by adjusting the tip height properly. Moreover, based on the strong vertical trapping ability and the relatively weak lateral trapping ability of the tip, we propose a simple method to realize a reversible vertical manipulation of the Pt adatom from the highly coordinated sites, the kink and the step sites, of the stepped Pt（111） surface. All the vertical manipulations are completed using only the atomic force between the tip and the adatom, without the electric field.