Standard Parts Research Articles

Model Experimental Study of Man-Machine Interactive Robot-Assisted Craniotomy.

To evaluate the feasibility, safety, and accuracy of the new man-machine interactive robotic system in model experiment. The implantation of the 8 to 10 bone screws over the skull model obtained from real patient's digital imaging and communications in medicine (DICOM), three-dimensional spiral computed tomography (CT) scans were taken. The end of the robotic arm was replaced with standard parts (including marker ball) for cone beam computed tomography (CBCT) scanning. The marker ball and marker pin were segmented and marked and exported via txt format. The position of the robotic end and model was obtained through the conversion of spacious position of standard parts and the executive end was replaced eventually. The water balloon was placed inside the skull model to imitate the dura mater and the destruction was documented for the system's safety. The system accuracy was evaluated by the error between the actual drilling position and the virtual plan and selection of 14 points of the skull window of milling pathway, monitored intraoperatively via Micron Tracker system and the overall skull window overlapped percentage via Mimics. Five model experiments were successfully performed with the average registration time of 3 minutes without destruction of balloon. The error of the outer table was 0.85 ± 0.45 mm, the inner table was 0.78 ± 0.49 mm, the line segment error of milling cutter was 0.93 ± 0.50 mm and the overall skull window overlapped percentage was 97.37% ± 0.78%. The system shows safety, accuracy, and reliability which can be an optional assistant method for craniotomy in the future.

Design and Research of Automatic Tool Changer System for Multistation Spring Forming Machine

Currently, the spring machine tool is fixed by means of manual clamping and positioning by bolts. The automation of the tool change is low, and the accurate value of the tool position cannot be determined. The automatic tool change system for spring machine was designed by using the standard functional parts of the automatic tool change system of the machining center. It mainly includes the design of the automatic loose clamp device and that of the multispindle automatic tool change arm. After static analysis, the deformation of the automatic tool change arm is 0.153 mm, which satisfies the requirements for usage. Kinematic analysis of the designed automatic tool change arm was carried out. After actual verification, the designed automatic tool change system of spring machine realizes the functions of the tools automatic replacement and positioning of the spring machine, which improves the automation of the spring forming equipment.

A novel and effective method for cryogenic milling of polytetrafluoroethylene

Polytetrafluoroethylene (PTFE) is a typical material widely used in bearing, gaskets, gears, etc. of many various fields such as aeronautics, astronautics, and military. Traditionally, PTFE is manufactured by molding process, which is suitable for processing of large quantities and standard parts. And a deburring treatment is necessary after molding. For small-scale or special shape products, molding techniques require new molds which need long time period. In contrast, machining method can meet the requirements more efficiently. However, the traditional machining is prone to produce machining defects such as edge fins and burrs. In this paper, a novel and effective method for cryogenic machining is proposed. According to the experiment results, the cryogenic machining can effectively restrain the production of machining defects and subsurface damage layer. And the mechanism of defect suppression in cryogenic machining is revealed by analyzing the change of molecular structure and properties with temperature.

Acoustic Methods for Testing Gas Turbine Engine Blades

In this paper the application technology of the ultrasonic testing method in the process of the PS-90A aircraft engine manufacturing is considered. It is known that the development and implementation of monocrystalline turbine blades for aircraft gas turbine engines are aimed at ensuring the material effectiveness or increasing the blade service life in comparison with polycrystalline blades. It is achieved at the cost of the increased long-term material strength in the same temperature range. Based on the results of the process and metallographic studies analysis, it has been established that during the structure formation under the internal stress action, hot crystallization cracks with an opening from 3 to 8 μm or more and a length of 3 to 35 mm along the grain boundaries can appear. Grains formation in most blades happens with their subsequent exit to the lock end, a bridge. The formation of hot cracks most likely occurs at a large grain disorientation angle (more than 25°). Grain boundaries on blades with hot crystallization cracks are located, as a rule, on the bridge at the junction of the blade root with the blade shank (“bottleneck”) with orientation along the blade axis. The method of contact laser-ultrasonic flaw detection (CLUFD) was tested on blades in the region of bridges using both pilot samples and standard parts in order to solve an urgent production and technical problem, that is timely detection of hot crystallization cracks in rotating turbine engine blades at the manufacturing stage. The use of the phased antenna array technology (PAR) in combination with a portable X-32 flaw detector represents a new level of blade ultrasonic testing. The flaw detector operates in a wide frequency range, which allows solving a very large range of various ultrasonic testing problems. The advantages and possibilities of the PAR technology with the portable X-32 flaw detector can be considered on the example of the turbine blade lock testing. S-scan (sector-scan) makes it possible to interpret the received signals quickly and easily.

Extended Set of GoldenBraid Compatible Vectors for Fast Assembly of Multigenic Constructs and Their Use to Create Geminiviral Expression Vectors.

Methods for simple and fast assembly of exchangeable standard DNA parts using Type II S restriction enzymes are becoming more and more popular in plant synthetic and molecular biology. These methods enable routine construction of large and complex multigene DNA structures. Two available frameworks emphasize either high cloning capacity (Modular Cloning, MoClo) or simplicity (GoldenBraid, GB). Here we present a set of novel α-level plasmids compatible with the GB convention that extend the ability of GB to rapidly assemble more complex genetic constructs, while maintaining compatibility with all existing GB parts as well as most MoClo parts and GB modules. With the use of our new plasmids, standard GB parts can be assembled into complex assemblies containing 1, 5, 10 and up to theoretically 50 units in each successive level of infinite loop assembly. Assembled DNA constructs can be also combined with conventional binary GB-assemblies (1, 2, 4, 8… units). We demonstrate the usefulness of our framework on single tube assembly of replicating plant expression constructs based on the geminivirus Bean yellow dwarf virus (BeYDV).

Pseudo-holomorphic curves: A very quick overview

AbstractThis is a review article on pseudo-holomorphic curves which attempts at touching all the main analytical results. The goal is to make a user friendly introduction which is accessible to those without an analytical background. Indeed, the major accomplishment of this review is probably its short length.Nothing in here is original and can be found in more detailed accounts such as [6] and [8]. The exposition of the compactness theorem is somewhat different from that in the standard references and parts of it are imported from harmonic map theory [7], [5]. The references used are listed, but of course any mistake is my own fault.

3D reconstruction of line-structured light based on binocular vision calibration rotary axis.

High-precision 3D topography measurement is essential to ensure quality and performance of shaft parts. Generally, the main difficulty of measuring rotary objects on a turntable is the low accuracy of axis calibration. To solve this problem, this study introduces two methods for calibrating the rotation axis of the turntable and proposes a method for reconstructing the 3D shape of the object by converting the rotation axis parameters of the binocular vision. A calibration camera is used to shoot a 2D checkerboard calibration board against the rotating table, and the calibration process of a high-precision space rotation axis is developed and implemented. This laser vision measurement system consists of a calibration camera, a measurement camera, and a rotation system. This system can realize reconstruction of the 3D shape of the object in accordance with the rotation axis parameters in any position. The experiment on measuring standard parts verifies the effectiveness of the algorithm. It provides a new idea for the measurement of rotary object shapes.

Use YeastFab to Construct Genetic Parts and Multicomponent Pathways for Metabolic Engineering.

Budding yeast, as a eukaryotic model organism, has well-defined genetic information and a highly efficient recombination system, making it a good host to produce exogenous chemicals. Since most metabolic pathways require multiple genes to function in coordination, it is usually laborious and time-consuming to construct a working pathway. To facilitate the construction and optimization of multicomponent exogenous pathways in yeast, we recently developed a method called YeastFab Assembly, which includes three steps: (1) make standard and reusable genetic parts, (2) construct transcription units from characterized parts, and (3) assemble a complete pathway. Here we describe a detailed protocol of this method.

Identification of CD34+/PGDFRα+ Valve Interstitial Cells (VICs) in Human Aortic Valves: Association of Their Abundance, Morphology and Spatial Organization with Early Calcific Remodeling.

Aortic valve interstitial cells (VICs) constitute a heterogeneous population involved in the maintenance of unique valvular architecture, ensuring proper hemodynamic function but also engaged in valve degeneration. Recently, cells similar to telocytes/interstitial Cajal-like cells described in various organs were found in heart valves. The aim of this study was to examine the density, distribution, and spatial organization of a VIC subset co-expressing CD34 and PDGFRα in normal aortic valves and to investigate if these cells are associated with the occurrence of early signs of valve calcific remodeling. We examined 28 human aortic valves obtained upon autopsy. General valve morphology and the early signs of degeneration were assessed histochemically. The studied VICs were identified by immunofluorescence (CD34, PDGFRα, vimentin), and their number in standardized parts and layers of the valves was evaluated. In order to show the complex three-dimensional structure of CD34+/PDGFRα+ VICs, whole-mount specimens were imaged by confocal microscopy, and subsequently rendered using the Imaris (Bitplane AG, Zürich, Switzerland) software. CD34+/PDGFRα+ VICs were found in all examined valves, showing significant differences in the number, distribution within valve tissue, spatial organization, and morphology (spherical/oval without projections; numerous short projections; long, branching, occasionally moniliform projections). Such a complex morphology was associated with the younger age of the subjects, and these VICs were more frequent in the spongiosa layer of the valve. Both the number and percentage of CD34+/PDGFRα+ VICs were inversely correlated with the age of the subjects. Valves with histochemical signs of early calcification contained a lower number of CD34+/PDGFRα+ cells. They were less numerous in proximal parts of the cusps, i.e., areas prone to calcification. The results suggest that normal aortic valves contain a subpopulation of CD34+/PDGFRα+ VICs, which might be involved in the maintenance of local microenvironment resisting to pathologic remodeling. Their reduced number in older age could limit the self-regenerative properties of the valve stroma.

FlopR: An Open Source Software Package for Calibration and Normalization of Plate Reader and Flow Cytometry Data.

The measurement of gene expression using fluorescence markers has been a cornerstone of synthetic biology for the past two decades. However, the use of arbitrary units has limited the usefulness of these data for many quantitative purposes. Calibration of fluorescence measurements from flow cytometry and plate reader spectrophotometry has been implemented previously, but the tools are disjointed. Here we pull together, and in some cases improve, extant methods into a single software tool, written as a package in the R statistical framework. The workflow is validated using Escherichia coli engineered to express green fluorescent protein (GFP) from a set of commonly used constitutive promoters. We then demonstrate the package’s power by identifying the time evolution of distinct subpopulations of bacteria from bulk plate reader data, a task previously reliant on laborious flow cytometry or colony counting experiments. Along with standardized parts and experimental methods, the development and dissemination of usable tools for quantitative measurement and data analysis will benefit the synthetic biology community by improving interoperability.

Близькі види гризунів надродини Muroidei у фауні України: таксономія, біогеографія, діагности-ка, екоморфологія

The results of the revision of the species composition and related knowledge of taxonomy, biogeography, diagnostics, variability and ecomorphology of polytypic groups of murine rodents, superfamily Muroidei, are presented. These are 5 former "large" species: "wood mice", "common mice", water voles, "shrub voles" and "common voles". Each of these groups is represented in the fauna of Ukraine and neighboring countries by 2–3 species. The two most difficult for revision and for background monitoring of fauna are "forest mice" and "common voles", each of which is represented in the fauna of the region by three morphologically very similar species of different kinship, among which one (the most genetically distant) is widely sympatric to the other two species that are allospecies. Among "forest mice", such species are Sylvaemus uralensis (= microps) against the pair S. sylvaticus + S. witherbyi (= S. falzfeini), and among the "common voles" it is Microtus levis (= rossiaemeridionalis) against the pair M. arvalis + M. obscurus. The other three pairs of species are generally more diverged (at least in terms of habitats and ecology, and in some cases morphology) and clearly less sympatric species. In the group of "common" mice, Mus "musculus" (s.l.), there is a pair of synanthropic and exanthropic forms — M. musculus and M. spicilegus (= M. sergii), which usually do not interact in nature, and therefore poorly diverged in morphology. In the group of "water voles" there is an allopatric pair, represented by the Carpathian-Roztochchian (essentially mountainous, associated with meadows) as well as plain hydrophilic forms, Arvicola scherman and A. amphibius (= A. terrestris). In the group of "shrub voles" there is a sympatric pair of species, one of them has limited distribution in the Carpathians (Terricola tatricus), but the other (T. subterraneus), being sympatric to the first in the Carpathians, also forms numbered populations in lowland forests, as in the forest zone as in the bairak steppe zone. Morphological differentiation between them is generally high, but the Eastern Carpathian form of Terricola tatricus is the smallest in a row of mountain forms of Terricola (multiplex, tatricus, zykovi), which was the reason for its long-term non-recognition in the fauna of Ukraine. For all species, descriptions are presented, including 5 standard parts for this series of publications: general remarks, taxonomy (including nomenclature), distribution (including biotopes), diagnostics (including variability), ecomorphology.Key words: small mammals, habitats, dominance, abundance of species.

Real-time process control of powder bed fusion by monitoring dynamic temperature field

This study aims to optimize the uniformity of the temperature field during sintering to improve part performance. A temperature-field monitoring system is established based on an infrared thermal imager and the temperature field data obtained during the sintering of a part can be measured in real time. The relationship among the sintering temperature field, sintering process parameters, and part performance is established experimentally. Subsequently, a temperature field monitoring and analysis system is constructed, and various sintering temperature-field control strategies are established for various part sizes. Finally, a dynamic control strategy for controlling the temperature field during sintering is proposed, experimentally validated, and fully integrated into a developed powder bed fusion (PBF) equipment. For eight-shaped standard parts, the range of sintering temperature field is optimized from 44.1 °C to 19.7 °C, whereas the tensile strength of the parts increased by 15.4%. For large-size H parts, localized over burning is eliminated and the final quality of the part is optimized. This strategy is critical for the optimization of the PBF process for large-sized parts, in particular in the large-sized die manufacturing industry, which offers promise in the optimization of part performance.

Digital Substation Evolution in the Journey of Smart Grid

IEC61850 as a globally accepted standard has paved the path for the realization of digital substations. A substation protection, automation, monitoring and control system based on the concepts of [EC61850 can be built faster, more efficiently, and more repeatably by replacing physical wiring with digital communications. This involves learning & understanding several parts of IEC61850 standard parts. [EC61850 standard parts consist of ten main parts with several other associated parts. While a utility decides to implement an “IEC61850 Digital substation”, the user must understand that to design such substation, the user not only has to understand the key terms, usage of standard but also what can be the potential benefits and what is the current trend in this space of digital substation. This paper presents architecture and evolution of the digital substation, present stage of implementation, at the same time potential benefits explained with some key case studies on protection, monitoring and control.

Exercising hybrid statistical tools GA-RSM, GA-ANN and GA-ANFIS to optimize FDM process parameters for tensile strength improvement

The properties of functional parts printed by additive manufacturing are highly dependent on various process parameters of the machine. The process parameters can be optimized by hybrid statistical tools to enhance the objective function. The present study investigates the tensile strength of Dogbone American Society for Testing and Materials (ASTM)-D638-V standardized parts fabricated by FDM 3D printer, using poly lactic acid (PLA) plus material. The test specimens were fabricated by varying three parameters: infill density (20–100%), speed (50–150mm/s) and temperature (190–210°C). For the parametric combination, response surface methodology (RSM) based central composite design (CCD) matrix was developed using second order polynomial fitting model. The maximum tensile strength of testing specimens on UNITEK-94100 universal testing machine (UTM) was recorded as 45.27MPa. Further, hybrid optimization techniques like genetic algorithm-artificial neural network (GA-ANN), genetic algorithm-response surface methodology (GA-RSM) and genetic algorithm-adaptive neuro fuzzy interface system (GA-ANFIS) are deployed to optimize these process parameters. Among these tools, the maximum accuracy of 99.89% obtained with GA-ANN which results in optimized parameters as infill density 100%, temperature 210°C, and speed 124.778mm/s to achieve the maximum tensile strength of 47.0212MPa. The results of this examination will facilitate the added substance producing units to choose the optimize factor value of input factors for FDM parts fabrication with improved mechanical properties. The hybrid developed models could be proposed for precise prediction and optimization of other process parameters and results for any industrial application problems.

A dual piezoelectric energy harvester with contact and non-contact driven by inertial wheel

In this paper, a dual piezoelectric energy harvester with contact and non-contact driven by inertial wheel is designed to explore relationship between the mass of inertia wheel and the generator performance. This harvester consists of rectangular and circular lead zirconate titanate (PZT) plates, magnet and other support structure. The model is simplified and analyzed. The supporting structure of the energy harvester is manufactured by 3D printing technology, and the standard parts such as bolts are assembled. The test system is built and the prototype is tested under different rotation speed (from 100 to 1300 r/min) and inertia wheel mass (227, 287, 348 and 407 g). This study has shown that under constant driving conditions (1000 r/min), the optimal peak-to-peak voltage and root-mean-square power are 36.07 V, 5.31 V and 5.47mW, 0.05mW across the 5kΩ resistor. Moreover, the optimal root-mean-square voltage and power are 4.87 V, 613.01 mV and 1.15mW, 21.04 μW across the 10kΩ driven through an inertial wheel. Moreover, the energy conversion efficiency of the energy harvester is 18.27% driven at the inertial wheel of 407 g. Therefore, this energy harvester can be used to collect the energy stored during the idling of the inertia wheel to supply sensor.

A review of laser engineered net shaping (LENS) build and process parameters of metallic parts

Purpose This paper aims to present a comprehensive review of the laser engineered net shaping (LENS) process in an attempt to provide the reader with a deep understanding of the controllable and fixed build parameters of metallic parts. The authors discuss the effect and interplay between process parameters, including: laser power, scan speed and powder feed rate. Further, the authors show the interplay between process parameters is pivotal in achieving the desired microstructure, macrostructure, geometrical accuracy and mechanical properties. Design/methodology/approach In this manuscript, the authors review current research examining the process inputs and their influences on the final product when manufacturing with the LENS process. The authors also discuss how these parameters relate to important build aspects such as melt-pool dimensions, the volume of porosity and geometry accuracy. Findings The authors conclude that studies have greatly enriched the understanding of the LENS build process, however, much studies remains to be done. Importantly, the authors reveal that to date there are a number of detailed theoretical models that predict the end properties of deposition, however, much more study is necessary to allow for reasonable prediction of the build process for standard industrial parts, based on the synchronistic behavior of the input parameters. Originality/value This paper intends to raise questions about the possible research areas that could potentially promote the effectiveness of this LENS technology.

A Novel Plug and Play Robotic Dynamometer to Assess Skeletal Muscle Contractile Function and Perform Plyometric Exercise in Live Mice

OBJECTIVEOur goal was to develop a user‐friendly, all in one instrument, which can be used in longitudinal studies of mice, to assess contractile torque produced by the ankle dorsiflexor muscles and perform forced plyometric exercise on this muscle group.METHODSWe repurposed a commercial, STEM Education robotics kit, which contains a microcontroller, stepper motors and modular parts, to build a robotic dynamometer. We connected two stepper motors in parallel for optimal driving torque. The axle that connected the motors was linked in series to a torque cell and footplate. Through a commercial plug and play data acquisition device connected to a PC through a USB port, we were able to visualize real‐time data from the torque cell, and record data as needed. We wrote custom routines in the programming language of the robotics kit to perform four sets of ten stretch‐shortening plyometric contractions of the ankle dorsiflexors, at an angular velocity of 300 degrees/s, through a range of 90–160 degrees of plantar flexion and dorsiflexion. During ankle movement produced by the robotic dynamometer, the dorsiflexor muscles were tetanized with subcutaneous needle electrodes connected to an electrical stimulator. To test our rig, we studied four, healthy, 1‐yr old, male, C57BL/6J mice. We performed all testing and training of live animals under general anesthesia induced and maintained by inhaled isoflurane (2–5% to effect).RESULTSWe found that plyometric exercise performed on our dynamometer induced a significant loss of contractile torque immediately after exercise (2816 ± 222 mNmm before exercise versus 2046 ± 87 mNmm after exercise; *, p < 0.001). At 3 days post‐exercise, contractile torque was still lower than pre‐exercise levels (2322 ± 143 mNmm at Day 3; *, p = 0.002), but was significantly greater than immediate post‐exercise levels (#, p = 0.038). Histological studies (hematoxylin and eosin staining) of cross sections of the injured tibialis anterior muscle revealed that 9.6 ± 4 % of the cross sectional area was damaged (pale and disrupted cytoplasmic staining of muscle fibers).CONCLUSIONOur novel robotic dynamometer is suitable for assessing contractile function and performing forced plyometric exercise on living mice. Since our rig is made from a commercial STEM Education robotics kit, a plug and play data acquisition system, and other standard parts, it is not only user‐friendly, but is also modular in nature and therefore helps reduce machine to machine variability.Support or Funding InformationNIH R03HD091648 from NICHD and a FRAP award from EACPHS Wayne State University to JARContractile Torque and Histological DataFigure 1

ОБРАБОТКА СОПРЯЖЕННЫХ ПОВЕРХНОСТЕЙ В ПЕРЕСЕКАЮЩИХСЯ КАНАЛАХ

The purpose of the work is the application of a non-profiled electrode-brush for mating surfaces machining including that in crossed channels. To achieve the goal set there were problems under solution: the development of essential equipment, electrode-tools, the selection of working environment, the optimization of combined machining modes. To solve the problems set there are used basis regulations of the theory: electric and combined methods of machining, the mathematical apparatus of probability theories and mathematical statistics. In the paper the developed and manufactured plants and electrode-tools are shown. The recommended machining conditions, working environment are shown. The equipment is presented with a small-size plant for high-speed machining with an electrode-brush and a portable plant fixed on a drill rod that with the use of operating fluid recommended allows reducing considerably the terms and cost of metal cutting equipment updating for machining with electric field imposition. In the paper there are considered standard parts: nozzles, ejector bodies, parts of piping hydro-systems. The results of machining parts with crossed channels are shown. The application of processing by an electrode-brush with high circumferential velocities with regard to the work-piece from 35 m/sec and higher allows manufacturing products with the set values. The application of an electrode-brush is efficient for mating surfaces combined machining.

Synthetic DNA Assembly Using Golden Gate Cloning and the Hierarchical Modular Cloning Pipeline.

Methods that enable the construction of recombinant DNA molecules are essential tools for biological research and biotechnology. Golden Gate cloning is used for assembly of multiple DNA fragments in a defined linear order in a recipient vector using a one-pot assembly procedure. Golden Gate cloning is based on the use of a type IIS restriction enzyme for digestion of the DNA fragments and vector. Because restriction sites for the type IIS enzyme used for assembly must be present at the ends of the DNA fragments and vector but absent from all internal sequences, special care must be taken to prepare DNA fragments and the recipient vector with a structure suitable for assembly by Golden Gate cloning. In this article, protocols are presented for preparation of DNA fragments, modules, and vectors suitable for Golden Gate assembly cloning. Additional protocols are presented for assembly of defined parts in a transcription unit, as well as the stitching together of multiple transcription units into multigene constructs by the modular cloning (MoClo) pipeline. © 2020 The Authors. Basic Protocol 1: Performing a typical Golden Gate cloning reaction Basic Protocol 2: Accommodating a vector to Golden Gate cloning Basic Protocol 3: Accommodating an insert to Golden Gate cloning Basic Protocol 4: Generating small standardized parts compatible with hierarchical modular cloning (MoClo) using level 0 vectors Alternate Protocol: Generating large standardized parts compatible with hierarchical modular cloning (MoClo) using level -1 vectors Basic Protocol 5: Assembling transcription units and multigene constructs using level 1, M, and P MoClo vectors.

You Need More Than Cookbooks [White Hot

You don’t learn how to cook from a cookbook.” This came to me while planning the teaching of this past semester’s power electronics project lab. In a previous column, I talked about teaching a project lab at the University of Colorado–Boulder for master’s students who were going into industry and not continuing for a Ph.D. degree. The goal of the project lab is for the students to do an original design project under conditions as similar to industry as possible. Rather than a weekly “build this, take data, write a report” of the typical university lab class, these students are given a specification and a schedule. The students are told “what,” they are not told “how.” They are also given a standard parts library, component derating guidelines, and product safety requirements. Some of the instructional objectives are learning to design with ac mains power, learning to design for a wide range of operation of both input voltage and output load, and learning how to debug an original design. The major goal of the class is to demonstrate working hardware at the end of the semester. The project is a 25-W constantcurrent output LED driver that must work from a universal ac input (85– 264 Vac) and vary the LED current from 0 to 1,200 mA, as the dimming control voltage varies from 0 to 10 Vdc.