Precise Design and Stress Analysis of Straight Conical Gear

Variable section sweeping with sphere involutes is used to generate the precise model of tooth profile. The contact and bending stress of a straight conical gear set with static bearing contact during a meshing cycle is studied using finite element method. Numerical results and comments are presented, revealing that the edge contact causes stress concentration and the gear tooth profile needs further modification.

Visualized and precise design of artificial small RNAs for regulating T7 RNA polymerase and enhancing recombinant protein folding in Escherichia coli

Small non-coding RNAs(sRNAs)have received much attention in recent years due to their unique biological properties,which can efficiently and specifically tune target gene expressions in bacteria.Inspired by natural sRNAs,recent works have proposed the use of artificial sRNAs(asRNAs)as genetic tools to regulate desired gene that has been applied in several fields,such as metabolic engineering and bacterial physiology studies.However,the rational design of asRNAs is still a challenge.In this study,we proposed structure and length as two criteria to implement rational visualized and precise design of asRNAs.T7 expression system was one of the most useful recombinant protein expression systems.However,it was deeply limited by the formation of inclusion body.To settle this problem,we designed a series of asRNAs to inhibit the T7 RNA polymerase(Gene1)expression to balance the rate between transcription and folding of recombinant protein.Based on the heterologous expression of Aspergillus oryzae Li-3 glucuronidase in E.coli,the asRNA-antigene1-17bp can effectively decrease the inclusion body and increase the enzyme activity by 169.9%.

Precision Design for Machine Tool Based on Error Prediction

Digitization precision analysis is an important tool to ensure the design precision of machine tool currently. The correlative research about precision modeling and analysis mainly focuses on the geometry precision and motion precision of machine tool, and the forming motion precision of workpiece surface. For the machine tool with complex forming motion, there is not accurate corresponding relationship between the existing criterion on precision design and the machining precision of workpiece. Therefore, a design scheme on machine tool precision based on error prediction is proposed, which is divided into two-stage digitization precision analysis crucially. The first stage aims at the technology system to complete the precision distribution and inspection from the workpiece to various component parts of technology system and achieve the total output precision of machine tool under the specified machining precision; the second stage aims at the machine tool system to complete the precision distribution and inspection from the output precision of machine tool to the machine tool components. This article serves YK3610 gear hobber as the example to describe the error model of two systems and basic application method, and the practical cutting precision of this machine tool achieves to 5-4-4 grade. The proposed method can provide reliable guidance to the precision design of machine tool with complex forming motion.

Investigation into precision engineering design and development of the next-generation brake discs using Al/SiC metal matrix composites

Substantially lightweight brake discs with high wear resistance are highly desirable in the automotive industry.This paper presents an investigation of the precision-engineering design and development of automotive brake discs using nonhomogeneous Al/SiC metal-matrixcomposite materials.The design and development are based on modeling and analysis following stringent precision-engineering principles,i.e.,brake-disc systems that operate repeatably and stably over time as enabled by precision-engineering design.The design and development are further supported by tribological experimental testing and finite-element simulations.The results show the industrial feasibility of the innovative design approach and the application merits of using advanced metal-matrix-composite materials for next-generation automotive and electric vehicles.

The Relationship between Interchangeability Standards and Precision Design in Teaching a Course on Interchangeability and Measurement Techniques

This article discusses some views on the relationship between carrying out and applying standards and precision design and the teaching of a course on interchangeability and measurement techniques. It points out that while emphasizing precision design, we should not underrate the significance of interchangeability and standardization. Although there are presently many teaching models available for such courses, each course should be designed separately to preserve its systematic character and integrality. As well, the development of students' abilities in precision design and the application of standards should be strengthened in experimental lessons within each course.

Forming-Precision-Driven Structure Design of Hydraulic Press: Methodology and Case Study

The structure stiffness of presses has great effects on the forming precision of workpieces, especially in near-net or net shape forming. Conventionally the stiffness specification of presses is empirically determined, resulting in poor designs with insufficient or over sufficient stiffness of press structures. In this paper, an approach for the structure design of hydraulic presses is proposed, which is forming-precision-driven and can make presses costeffective by lightweight optimization. The approach consists of five steps:(1)the determination of the press stiffness specification in terms of the forming precision requirement of workpieces;(2)the conceptual design of the press structures according to the stiffness and workspace specifications, and the structure configuration of the press;(3)the prototype design of the press structures by equivalently converting the conceptual design to prototypes;(4)the selection of key structure parameters by sensitivity analysis of the prototype design; and(5)the optimization of the prototype design. The approach is demonstrated and validated through a case study of the structure design of a 100 MN hydraulic press.

Workflow and Principles for Precisely Designing a Custom-Made Polyetheretherketone Implant Applied in Irregular Craniofacial Bone Defects

Irregular craniofacial bone defects caused by craniofacial fractures always result in craniofacial bone and contour asymmetry and should therefore be reconstructed.Polyetheretherketone(PEEK)is an ideal substitute for autologous bone grafts and has been widely used in craniofacial bone defect reconstruction.The precise design of custom-made PEEK implants is particularly important to optimise reconstruction.Herein,the workflow and principles for the design and manufacture of PEEK implants are summarised,and a protocol for the precise design of an irregular craniofacial bone defect PEEK implant is presented.According to the method and principles,the design flow was efficient and could be standardised,and design errors could be avoided as much as possible.

Elastin-like polypeptide fusion for precision design of protein-polymer conjugates with improved pharmacology

Therapeutic proteins and peptides are characteristic by their high biological activity and specificity,but their clinical uses are bottlenecked by their poor stability,short in vivo half-life and immunogenicity[1].One typical example is recombinant human interferon alpha(IFN-α),FDA-approved and widely used in treatments of viral diseases and cancer,yet its short plasma half-life(t1/2=2-4 h)necessi-

A high precision programmable bandgap voltage reference design for high resolution ADC

A programmable high precision bandgap reference is presented, which can meet the accuracy requirements for all technology corners while a traditional bandgap reference cannot.This design uses SMIC 0.18 μm 1P4M CMOS technology.The theoretically achievable temperature coefficient is close to 0.69 ppm/°C over the whole temperature range.

Causal gene identification and desirable trait recreation in goldfish

Goldfish(Carassius auratus) have long fascinated evolutionary biologists and geneticists because of their diverse morphological and color variations.Recent genome-wide association studies have provided a clue to uncover genomic basis underlying these phenotypic variations,but the causality between phenotypic and genotypic variations have not yet been confirmed.Here,we edited proposed candidate genes to recreate phenotypic traits and developed a rapid biotechnology approach which combines gene editing with high-efficiency breeding,artificial gynogenesis,and temperature-induced sex reversal to establish homozygous mutants within two generations(approximately eight months).We first verified that low-density lipoprotein receptorrelated protein 2B(lrp2a B) is the causal gene for the dragon-eye variation and recreated the dragon-eye phenotype in side-view Pleated-skirt Lion-head goldfish.Subsequently,we demonstrated that the albino phenotype was determined by both homeologs of oculocutaneous albinism type II(oca2),which has subfunctionalized to differentially govern melanogenesis in the goldfish body surface and pupils.Overall,we determined two causal genes for dragon-eye and albino phenotypes,and created four stable homozygous strains and more appealing goldfish with desirable traits.The developed biotechnology approach facilitates precise genetic breeding,which will accelerate re-domestication and recreation of phenotypically desirable goldfish.

Experimental Setup for the Investigation of Reproducibility of Novel Tool Changing Systems in Nanofabrication Machines

Nanomeasuring machines developed at the Technische Universitat Ilmenau enable three-dimensional measurements and manufacturing processes with the lowest uncertainties.Due to the requirements for these processes,a highly reproducible and long-term stable tool changing system is needed.For this purpose,kinematically determined couplings are widely used.The state-of-the-art investigations on those are not sufficient for the highest demands on the reproducibility required for this application.A theoretical determination of the reproducibility based on analytical or numerical methods is possible,however not in the desired nanometer range.Due to this,a measurement setup for the determination of the reproducibility in five degrees of freedom with nanometer uncertainty was developed.First,potential measuring devices are systematically examined and measurement principles were developed out of this.A three-dimensional vector-based uncertainty analysis is performed to prove the feasibility of the measurement principle and provides a basis for further design.As a result,a transla-tory measurement uncertainty of 10 nm and a rotatory uncertainty of 11 nrad can be reached.Afterwards,the measurement setup is designed,focusing on the metrological frame and the lift-off device.The developed setup exceeds the uncertainties of the measurement setups presented in the state-of-the-art by an order of magnitude,allowing new in-depth investigations of the reproducibility of kinematic couplings.