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Whirling, in which a rotating workpiece is machined by rotating tools around the workpiece with an eccentricity between the centers of the workpiece and the tool rotations, has been generally performed in threading. The whiling mechanism is applied to polygon machinings in this study. In proposed machining, the ratio of workpiece rotation rate to tool rotation rate is set to be n : 1 to machine n polygon prism. An analytical model was established to control the machining shape. The cutting tests, then, were conducted to verify the presented machining with the analytical model. Machining examples of triangular, square and pentagonal prisms were demonstrated in whirling. The effect of the tool rotation radius on the curvature of the workpiece surface is discussed in measurement of the machined shapes.

International audience; Polymeric particles are strong candidates for designing artificial materials capable of emulating the complex twisting-based functionality observed in biological systems. In this letter, we provide the first detailed investigation of the swelling behavior of bipolar polymer liquid crystalline microparticles. Deswelling from the spherical bipolar configuration causes the microparticle to contract anisotropically and twist in the process, resulting in a twisted spindle shaped structure. We propose a model to describe the observed spiral patterns and twisting behavior.

In this chapter we will look at several facilities supported by both the threading and multiprocessing libraries that allow for synchronisation and cooperation between Threads or Processes.

To use the Threading Building Blocks (TBB) library effectively, it is important to understand how it supports and augments the C++ standard. We discuss three aspects of TBB’s relationship with standard C++ in this chapter

When developing parallel applications with the Threading Building Blocks library, we create tasks by using the high-level execution interfaces or the low-level APIs. These tasks are scheduled by the TBB library onto software threads using work stealing. These software threads are scheduled by the Operating System (OS) onto the platform’s cores (hardware threads). In this chapter, we discuss the features in TBB that let us influence the scheduling choices made by the OS and by TBB. Thread-to-core affinity is used when we want to influence the OS so that it schedules the software threads onto particular core(s). Task-to-thread affinity is used when we want to influence the TBB scheduler so that it schedules tasks onto particular software threads. Depending on what we are trying to achieve, we may be interested in one kind of affinity or the other, or a combination of both.

This paper focuses on the development of effective methodology to machine bone screw on a 5-axis sliding head machine. Bone screw has a complex design involving special thread profiles and contours. This calls for complex machining processes such as taper threading with constant OD, slot milling, profile milling and ID threading. The threading consists of unique profile including corner radius and thread angle. Most critical operation is threading over the length of 30–120 mm. Two manufacturing concepts are envisaged initially, one being thread whirling and the other being usage of form tool. To achieve cost-effective solution, form threading is conceptualized. Total design and manufacturing, process and selection of tooling, programming and experimentation with prototype development constitute the major part of project work.

The following two methods of formation of threaded surfaces on FDM components are considered: cutting with a hand-guided threading tool in a workpiece fabricated by 3D printing and 3D printing of components with initially simulated threaded surfaces in inner and outer cylindrical surfaces. The fabrication of threaded surfaces by 3D is found to be promising as compared to cutting. Printing is shown to be adjusted so that threaded components are produced under specific conditions, which differ from the printing conditions of the base material.

The Vienna Ab initio Simulation Package (VASP) is a widely used electronic structure code that originally exploits process-level parallelism through the Message Passing Interface (MPI) for work distribution within and across nodes. Architectural changes of modern parallel processors urge programmers to address thread- and data-level parallelism as well to benefit most from the available compute resources within a node. We describe for VASP how to approach for an MPI + OpenMP parallelization including data-level parallelism through OpenMP SIMD constructs together with a generic high-level vector coding scheme. We can demonstrate an improved scalability of VASP and more than 20% gain over the MPI-only version, as well as a 2x increased performance of collective operations using the multiple-endpoint MPI feature. The high-level vector coding scheme applied to VASP's general gradient approximation routine gives up 9x performance gain on AVX512 platforms with the Intel compiler.

In this time of robotization advances fabricating parts have put levels of popularity on quick and dependable creation techniques. This testing of clutch plate is done through axial fatigue rig test bench. This work is the evaluation and analysis of the existing thread hole in base plate. The current axial fatigue rig test bench uses threading type of fixtures for holding the workpiece in the proper position. The evaluated system uses vertical grub screw for holding the workpiece instead of directly fixing the clutch plate in the base plate. Then both working principles are interpreted for their unique merits and demerits. Comparison of both working components was made based on their performance efficiency and their merits and demerits. The result is given based on the comparison between the two fixtures of clutch.

We describe a method for constructing developable bands with N≥3 half twists. Each band is formed by threading a flat rectangular strip through a scaffold made from identical circular cylinders and smoothly connecting its short ends. The N cylinders in a scaffold are arranged with N-fold rotational symmetry. The number of half twists in a band is equal to the number N of cylinders in its scaffold and each band inherits the symmetry of its scaffold. Each scaffold admits a family of bands of the same length but variable width up to a maximum value determined by the features of the scaffold. Apart from orientable and nonorientable unknots, our method allows for the construction of bands with the topology of torus knots. We detail the geometric properties of the construction, discuss certain fundamental restrictions that must be met to ensure constructability, and calculate the elastic bending energy of each band. The rotational symmetry underlying the construction is essential for obtaining the presented bands, as the general non-symmetric problem is even more complex and has not yet been investigated. The bands and their corresponding scaffolds can be used as structural elements in practical applications, one of which we describe and analyze. The construction serves as a basis for a general framework for building a large variety of scaffolds and the corresponding unstretchable bands. Together, these assemblies can be used in architectural, interior, and machine design. They also open new avenues for the layout of conveyor belts in factories, airports, and other settings.

The influence of introducing a SiGe/Ge superlattice (SL) between Ge layers and Si substrate for the sake of the reduction of the threading dislocation density (TDD) without additional annealing is investigated. By introducing the SiGe/Ge SL and optimizing the layer stack, the TDD of the Ge layer becomes ∼1/3. In the case of 2.8 μm thick Ge without introducing the SiGe/Ge SL, the TDD at the surface is 7.6 × 108 cm−2. A slight TDD reduction is observed by introducing a Si0.2Ge0.8/Ge SL between the Si substrate and the Ge layer. By inserting 5, 10 and 20 cycles of Si0.2Ge0.8/Ge, the TDD is reduced to 7.1 × 108, 5.9 × 108 and 5.3 × 108 cm−2, respectively. The lateral lattice parameters of these SLs are ∼5.656 Å, which is a smaller value compared to that of bulk Ge, indicating plastic relaxation by misfit dislocation formation. Further TDD reduction is realized with increasing Si concentration in the SiGe/Ge SL without changing the cycle of the SL. However, surface roughening due to pit formation occurs if the Si concentration in the SL is higher than 50% because of increased strain at the interfaces between SiGe and Ge. With increasing SiGe and Ge thickness ratio in the SL layer and maintaining periodicity and cycles, the TDD is reduced to 2.8 × 108 cm−2 without degrading the surface roughness. This improvement is related to a relaxation of the SiGe/Ge SL by plastic deformation.

The external voltage-driven polymer translocation through a conical pore (with a large opening at the entry and a small tip at the exit) is studied by using the Langevin dynamics simulation in this paper. The entire translocation process is divided into an approaching stage and a threading stage. First, the approaching stage starts from the polymer entering the large opening and ends up at a terminal monomer reaching the pore tip. In this stage, the polymer will undergo the conformation adjustment to fit the narrowed cross-sectional area of the pore, leading to three approaching modes: the non-stuck mode with a terminal monomer arriving at the pore tip smoothly, the weak-stuck mode for the polymer stuck inside the pore for a short duration with minor conformational adjustments, and the strong-stuck mode with major conformational changes and a long duration. The approaching times (the duration of the approaching stage) of the three approaching modes show different behavior as a function of the pore apex angle. Second, the threading stage describes that the polymer threads through the pore tip with a linear fashion. In this stage, an increase in the apex angle causes the reduction of the threading time (the duration of the threading stage) due to the increase in the driving force with the apex angle at the tip. Moreover, we also find that with the increase in the apex angle or the polymer length, the polymer threading dynamics will change from the quasi-equilibrium state to the non-equilibrium state.

This study proposed a pedicle screw design where the proximal 1/3 of the screw is unthreaded to improve fixation in posterior spinal surgery. This design was also expected to reduce the incidence of mechanical failure often observed when an unsupported screw length is exposed outside the vertebra in deformed or degenerated segments. The aim of this study was to evaluate the fatigue life of the novel pedicle screw design using finite element analysis and mechanical testing in a synthetic spinal construct in accordance with American Society for Testing and Materials (ASTM) F1717. The following setups were evaluated: (i) pedicle screw fully inserted into the test block (EXP-FT-01 and EXP-PU-01, full thread (FT), proximal unthread (PU)) and (ii) pedicle screw inserted but leaving an exposed shaft length of 7.6 mm (EXP-FT-02 and EXP-PU-02). Corresponding finite element models FEM-FT-01, FEM-FT-02, FEM-PU-01, and FEM-PU-02 were also constructed and subjected to the same loading conditions as the experimental groups. The results showed that under a 220 N axial load, the EXP-PU-01 group survived the full 5 million cycles, the EXP-PU-02 group failed at 4.4 million cycles on average, and both EXP-FT-01 and EXP-FT-02 groups failed after less than 1.0 million cycles on average, while the fatigue strength of the EXP-FT-02 group was the lowest at 170 N. The EXP-FT-01 and EXP-FT-02 constructs failed through fracture of the pedicle screw, but a rod fractured in the EXP-PU-02 group. In comparison to the FEM-FT-01 model, the maximum von Mises stress on the pedicle screw in the FEM-PU-01 and FEM-PU-02 models decreased by −43% and −27%, respectively. In conclusion, this study showed that having the proximal 1/3 of the pedicle screw unthreaded can reduce the risk of screw fatigue failure when used in deformed or degenerated segments.

Industrial threading processes that use cutting taps are in high demand. However, industrial conditions differ markedly from laboratory conditions. In this study, a machine-learning solution is presented for the correct classification of threads, based on industrial requirements, to avoid expensive manual measurement of quality indicators. First, quality states are categorized. Second, process inputs are extracted from the torque signals including statistical parameters. Third, different machine-learning algorithms are tested: from base classifiers, such as decision trees and multilayer perceptrons, to complex ensembles of classifiers especially designed for imbalanced datasets, such as boosting and bagging decision-tree ensembles combined with SMOTE and under-sampling balancing techniques. Ensembles demonstrated the lowest sensitivity to window sizes, the highest accuracy for smaller window sizes, and the greatest learning ability with small datasets. Fourth, the combination of models with both high Recall and high Precision resulted in a reliable industrial tool, tested on an extensive experimental dataset., Projects TIN2015-67534-P (MINECO/FEDER, UE) of the Ministerio de Economía Competitividad of the Spanish Governmentand project BU085P17 (JCyL/FEDER, UE) of the Junta de Castilla y Le ́on, both co-financed through European-Union FEDER funds and project IT-2005/00201 of the INNOTEK Program of the Basque Government

Influence of dislocations on diamond Schottky barrier diode characteristics of vertical structure p- layer/p+ substrate is studied. Devices are intentionally fabricated at locations corresponding to specific dislocations, stacking faults and growth sector boundaries observed using X-ray topography (XRT) prior to device fabrication. Devices fabricated on [001] threading dislocation area, and threading dislocation with stacking fault (SF) areas showed very large leakage current compared with devices without dislocations. Dislocation vectors of four devices having threading dislocations with SFs, are analyzed using XRT images and compared with current to voltage (I–V) characteristics. The number of threading dislocations and their types vary significantly, and there is not much difference in the I–V characteristics. Thus, threading dislocations are fatal to the device characteristics regardless of their dislocation directions, types, and number counts.

The conversion of threading screw dislocations (TSDs) to defects on the basal plane during SiC solution growth caused by macrostep advance is a key factor to improve crystal quality. We realized the TSD conversion in 4H-SiC C face solution growth by modification of the surface morphology including macrosteps by addition of 5 atom % Ti into pure Si solvent. Synchrotron X-ray topography revealed that the possibility of TSD conversion increased to about 10% with the addition of 5 atom % Ti. In addition, the TSD conversion ratio depends on the shape of the macrostep edge. The gentle slope hardly made TSD conversion. The elastic energy of dislocations in anisotropy crystals was postulated as an explanation for the influence of step shape on TSD conversion behavior.

Synchrotron X-ray Topography is a powerful technique to study defects structures particularly dislocation configurations in single crystals. Complementing this technique with geometrical and contrast analysis can enhance the efficiency of quantitatively characterizing defects. In this study, the use of Synchrotron White Beam X-ray Topography (SWBXT) to determine the line directions of threading dislocations in 4H–SiC axial slices (sample cut parallel to the growth axis from the boule) is demonstrated. This technique is based on the fact that the projected line directions of dislocations on different reflections are different. Another technique also discussed is the determination of the absolute Burgers vectors of threading mixed dislocations (TMDs) using Synchrotron Monochromatic Beam X-ray Topography (SMBXT). This technique utilizes the fact that the contrast from TMDs varies on SMBXT images as their Burgers vectors change. By comparing observed contrast with the contrast from threading dislocations provided by Ray Tracing Simulations, the Burgers vectors can be determined. Thereafter the distribution of TMDs with different Burgers vectors across the wafer is mapped and investigated.

The purpose of this study is to investigate the relationship between warp-knitted run-in values and process parameters such as yarn fineness, overlapping, underlapping, take-up density, total threading rate, and machine gauge. Run-in values of 52 samples with different process parameters were measured and analyzed in the method of response surface methodology (RSM) and multilayer perception (MLP). The results of RSM analysis show a significant influence of process parameters on warp-knitted run-in. Moreover, a predictive model is proposed base on the RSM, whose average error rate is confirmed to be 5.29%. In addition, the MLP analysis shows the sequence of influencing importance of process parameters form the high to low is underlapping (51.0%), overlapping (28.5%), take-up density (9.6%), machine gauge (4.7%), yarn fineness (4.0%), and total threading rate (2.2%).

Machining science is aimed at defining both cutting tools and machining conditions based on economic performance and to maintain workpiece surface integrity. Currently, machinists face a wide offer of turning, milling, drilling, and threading tools. Tools present a lot of similarities and light differences between them, being the latter the concealed reasons for a better or worse performance on difficult-to-cut alloys machining. However machinists had not useful methods for detecting which key tool aspects implies the best performance. The classic and expensive 'test-trial' method results non-viable due to the market exponential increase, both in size and specialization. This paper brings up an indirect method for seeking common features in the group of those tools with the best performance on machining Inconel 718. The method is divided into five stages, namely: (a) raw testing of a basic operation with a lot of commercial solutions for the same operation; (b) filtering of results to reduce the feasible solutions to a few ones, studying the common features of successful cases; (c) testing of these feasible solutions aimed at choosing the best insert or tool (d); and finally (e) full testing concerning all workpiece surface integrity issues. The proposed method provides knowledge based on the distilling of results, identifying carbide grades, chipbreakers shapes, and other features for having the best tool performance. All surface integrity effects are checked for the best solution. This new point of view is the only way for improving the difficult-to-cut alloys machining, reaching technical conclusions with industrial interest. This paper shows the method applied on Inconel 718 turning, resulting in a carbide grade with 10% cobalt, submicron grain size (0.5–0.8 µm) and hardness around 1760 HV, coating TiAlN monolayer with 3.5 µm thickness, chipbreaker giving 19° of rake angle that becomes 13° real one after insert is clamped on toolholder. Cutting edge radius after coating was 48 µm approximately. Cutting speed was 70 m/min higher in comparison with that recommended in handbooks.

In this article, a new method for the rapid and economical production of ‘nutless’ bolted joins is presented, using a combination of two hole-making techniques, namely, form drilling and form tapping. The combined method achieves a quick way for the production of threaded holes on couples of dissimilar metal alloys, as it is the case of steels and aluminium alloys. After the simultaneous form drilling on the aluminium–steel pairs and followed by form tapping, a fastener can be introduced and screwed for achieving a tight bolted joint, without any necessity of nut. However, form drilling and threading are performed consecutively in the same machine tool, reducing the whole process time. The process parameters were studied for reducing the gap between surfaces and producing a good cup for making the posterior threading. Then, mechanical testing of several test pieces resulted in a similar behaviour than traditional bolted joints. Finally, corrosion tests were performed for a better understanding of the joint manufactured. In this way, savings in time and money are derived from the application of the approach. Target markets for the new approach are the light boilermaking industry in order to eliminate either welding beads or classical bolted joints using nuts.

Conducted laboratory studies of the threading in the details of ship machinery and ship armatures from hard materials helped to create the modern technology of internal threads of small diameters cutting. The reasons that impede the processing of hard materials are find out. Presented are various designs of taps for cutting of internal threads and analyzed is their work. Noted are shortcomings of their designs resulting in creating a modern cutting pattern, allowing to minimize the shortages identified in the processing of hard materials. Practice shows that the machining of these materials is difficult because of their considerable tendency to work hardening during deformation, high viscosity, poor heat dissipation from the cutting zone. They have a low coefficient of thermal conductivity and low coefficient of workability relatively to tool steel. Therefore, processing technology and cutting conditions used for structural carbon steels, often are unacceptable to hard materials. The most difficult is tapping into the holes of small diameters up to 16 mm. The disadvantage of this technology is the low quality of threaded surfaces and an increased tendency to tap breakage. To improve threading performance in the details of the hard materials are developed advanced threading techniques.

Aim: To evaluate the use of Straight needle threading technique to perform frontalis sling by silk suture material as a surgical correction of severe blepharoptosis cases. Settings and Design: a prospective study was performed on patients who underwent 3-0 silk frontalis suspension using a Straight needle threading technique with an average of 8 months follow up period. Baker’s criteria for satisfactory results was used in which the correction of > = 1 mm from the normal side (or corrected side in bilateral ptosis). Patients and Methods: An eighty seven eyes in 67 patients were done, 25 eyes were operated on under local anaesthesia and 62 eyes under GA, 20 cases bilateral and 47 cases unilateral, 55.2% males (37 cases) and 44.8% females (30cases). The average age was 12 years (range 2-70 years). Statistical analysis was done by using the frequency values analysed by the program Statistical package for social sciences (SPSS) version 20 to analyse the results. Results: it was satisfactory in 76.4%, unsatisfactory in 23.6%, overcorrection 3.5%, under correction 15.3%, Entropion 0%, Lagophthalmus 4.8%, exposure keratitis 0%. Conclusion: the use of silk suture by straight needle threading technique is fast, easy, and low cost method to correct a complex problem like sever ptosis with a comparable aesthetic and functional results to other non- autologous materials, with good safety profile.

Bis(p-phenylene)-34-crown-10-based substituted macrocycles bearing a dibenzylammonium side arm form sailboat-shaped self-complexes, in which the arm of the substituted macrocycle sticks into the cavity of the crown ether instead of threading into it. On the basis of this simple system, we easily constructed controllable rotary switches. The decomplexation/recomplexation process was realized by acid–base stimuli, and the switching process was successfully used to control the dethreading/rethreading of paraquat as a guest through the cavity of the BPP34C10 moiety of the substituted macrocycles, which rendered them promising candidates for fabricating more novel interlocked structures and molecular devices.

Dislocation structures at the seed/grown-crystal interface in PVT-grown 4H-SiC crystals are investigated. The dislocation density is found to show a sharp increase at the interface and its main contribution is probably ascribable to TEDs which stem from BPDs generating at the interface through the structural transformation. Intense TEM observations reveal an intriguing in-plane distribution structure of the interface BPDs; the BPDs form a two-dimensional dislocation network comprising of {-1100} partial dislocations associated with expanded areas of stacking faults at the nodes of the network.

This paper describes 3D imaging of extended defects in 4H-SiC using optical second-harmonic generation (SHG) and two-photon-exited photoluminescence (2PPL). SHG selectively yields the 3D images of 3C-inclusions in a 4H-SiC epilayer, while 2PPL provides 3D images of 3C-inclusions, 8H stacking faults and single Shockley stacking faults. 2PPL band-edge emission visualizes dislocation lines of threading screw dislocations and threading edge dislocations, the tilt angles of which are evaluated.

X-ray topography shows that selective KOH etching after CVD growth of n-type epilayers on highly N doped 4H SiC substrates can be used to reliably map pure and mixed Threading Screw Dislocations (TSD). The influence of the mapping grid density and the wafer position in the crystal on the average TSD density are investigated. A reliable mapping of TSD contributed to the development of 100mm SiC wafers with average TSD density down to 200 cm-2.

Understanding the growth and propagation of defects in SiC remains of interest in an effort to continue to improve device performance. A post-growth boule heat-treatment revealed to form micropipe pairs from apparent single screw dislocations is reviewed. In the treated samples almost no 1c threading screw dislocations were found. Instead, micropipe pairs were observed in similar densities to 1c threading screw dislocations in non-heat treated samples. It is hypothesized that the elevated temperatures allowed for enhanced dislocation mobility, enabling the transition.

Structural transformation from threading screw dislocations (TSDs) to stacking faults (SFs) has been investigated for PVT-grown 4H-SiC single crystals using X-ray topography and transmission electron microscopy (TEM). The transformation of TSDs is induced by the structural interference with bunched surface macrosteps over 100 nm in height. The stacking sequence of a SF was determined to be (433) in Zadanov's notation by using high-resolution TEM. Our detailed analyses revealed that the (433) stacking structure can be constructed by a combination of five faults including both four Frank type faults and one Shockley type fault.

We characterized threading screw dislocations to investigate the influence on device performance. The Burgers vectors of the threading screw dislocations (a total of 28dislocations) in 4H-SiC were determined by large-angle convergent-beam electron diffraction. A new type of TSD, b=c+2a dislocation was identified. And all of the four types of TSD predicted were identified. The frequency of their occurrence observed experimentally is in good agreement with theoretical prediction. In addition, we investigated relations of Burgers vector and the dislocation line direction. It has been confirmed that the Burgers vector of TSD does not necessarily coincide with the direction of dislocation lines. Looking ahead, we need to investigate how the angle between Burgers vector and dislocation line influence device performance.

The aim of this work is to develop an experimental device useful to evaluate the friction coefficient in triangular thread joints (M12) manufactured with rolling and machining processes, and therefore, to relate precisely the clamping force to the tightening torque. Experimental static tests of clamp force during 10 tightening–loosening cycles were applied to specific threaded specimens obtained with the rolling and machining process. To analyze the mechanical and tribological behaviors of the manufactured threads, the torque coefficient (K) (nut factor), the average friction coefficient (μ m ), and the clamped force (F) have been evaluated during 10 cycles of tightening–loosening. The results of this study showed that the range of the variability of the torque coefficient and friction coefficient is between 0.151 and 0.54 and from 0.19 to 0.69 for the rolled thread, respectively. However, these coefficients are between 0.187 and 0.55 and from 0.25 to 0.72 for the machined thread, respectively. The clamping force preserves a linear relationship with the tightening torque and decreases as the number of tightening increases. The use of the rolling process to manufacture the thread joint can preserve a higher mechanical resistance and ameliorate the tribological behavior of the thread compared to the machining process.

One of the machining methods able to ensure a high material removal rate in the case of obtaining threaded surfaces is the whirling machining. In order to obtain a high accuracy of the machined surface and low values of the surface irregularities, an adequate selection of the machining parameters is necessary. A geometrical analysis of generating the surfaces in case of applying the whirl threading was developed. Geometrical and kinematical conditions were considered and software was used in order to modelling the process and to highlight the influence exerted by some process input factors on the machining errors and height of the surface irregularities.

In order to mitigate the formation of threading dislocations in an In0.1Ga0.9Sb heteroepitaxial buffer layer grown on a (001) GaSb substrate, an AlSb blocking layer was grown within the buffer layer. Transmission electron microscopy measurements revealed that the film with the AlSb blocking layer had a significantly lower threading dislocation density than a buffer layer of equivalent thickness in the absence of the blocking layer. Because the AlSb blocking layer is of greater mechanical stiffness than the In0.1Ga0.9Sb buffer layer, attractive image forces that act to draw dislocations to the film surface are countered by repulsive image forces traceable to the In0.1Ga0.9Sb/AlSb interface. These experimental results are consistent with calculations based on anisotropic elasticity theory for repulsive image forces acting on a dislocation beneath the blocking layer.

In addition to pure threading screw dislocations (TSDs), the presence of threading mixed dislocations (TMDs) (with a component) has been reported both in 4H-SiC axial slices (wafers cut parallel to the growth axis) and in commercial offcut wafers (cut almost perpendicular to the growth axis). In this paper, we first demonstrate a method to quickly distinguish TMDs from TSDs in axial slices via synchrotron white-beam x-ray topography. Since such axial slices are usually not available for commercial purposes, a systematic method is then developed and demonstrated here to unambiguously determine the Burgers vectors of TMDs in 4H-SiC commercial offcut wafers. In this second study, both synchrotron monochromatic-beam x-ray topography and ray-tracing simulation are used. The x-ray topographs were recorded using grazing-incidence geometry. The principle of this method is that the contrast of dislocations on different reflections varies with the relative orientation of Burgers vectors with respect to the diffraction vectors. Measurements confirm that, in a commercial offcut wafer, the majority of the threading dislocations with screw component are mixed-type dislocations.

The paper presents the evaluation of the drillability characteristics of the Ti6Al4 V titanium alloy produced through the Additive Manufacturing (AM) technology called Direct Metal Laser Sintering (DMLS). Holes of 1.6 mm diameter were drilled on a 5-axis high-precision micro-milling machine under dry cutting conditions at varying cutting speed and feed rate. A specific measurement procedure was developed to quantify and compare the most representative geometrical features (diameter and perpendicularity) of the machined holes as well as the quantification of burrs. The influence of the AM material on the geometrical quality of high precision holes is discussed, taking into account the requirements of the following threading operations. Finally, thread milling experiments were carried out to prove the threading feasibility and performances based on the previous drilling experiments. From the results within the tested range of cutting conditions, the lowest values of the cutting speed and feed rate seem to be the best trade-off for achieving the required hole quality.

Soft errors have become a serious cause of concern with reducing feature sizes. The ability to accommodate complex, Simultaneous Multithreading (SMT) cores on a single chip presents a unique opportunity to achieve reliable execution, safe from soft errors, with low performance penalties. In this context, we present FluidCheck , a checker architecture that allows highly flexible assignment and migration of checking duties across cores. In this article, we present a mechanism to dynamically use the resources of SMT cores for checking the results of other threads, and propose a variety of heuristics for migration of such checker threads across cores. Secondly, to make the process of checking more efficient, we propose a set of architectural enhancements that reduce power consumption, decrease the length of the critical path, and reduce the load on the Network-on-Chip (NoC). Based on our observations, we design a 16 core system for running SPEC2006 based bag-of-tasks applications. Our experiments demonstrate that fully reliable execution can be attained with a mere 27% slowdown, surpassing traditional redundant threading based techniques by roughly 42%.

The existing manufacturing technology of small mechanisms elements (gears, gear racks, displacers, bushings, precise mechanical parts, implants) is based on standard material removal techniques (turning, milling etc.). The problem is a variety of a polyamide materials chemical composition. Each additive has a significant influence to the material machinability in technological process. In a result it changes also resistance for melting of material in heat influence area. The method is based on automatically adaptation of parameters with author GRIP NC software and repeatable check of outer layer surface quality in various conditions and cutting strategies. Siemens NX Manufacturing module was used as a tool for operation simulation, parameters correction and G-code post processing tool. Fast G-code Generations gives possibility not only of parameters correction (that can be easily made in G-code itself) but also to optimize trajectory. Iterative comparison of surface roughness and chip flow monitoring were the main criteria that decided of cutting speed modification. On the output of the proposed method the proper cutting parameters table was prepared as well as a set of manufacturing recommendations. The case study is oriented to three polyamide modified materials: ERTHALON 6 PLA PA 6G, ERTALON LFX PA 6G (oil additive) NYLATRON GSM IPA 6 (MoS2 additive). Each material has a different set of fitted cutting parameters. Achieved results could be the guidance and provide proper outer surface roughness for (rough and finish) cutting operations like: axial and radial turning, threading and cutting.

Realizing the digital thread is essential for linking and orchestrating data across the product lifecycle in smart manufacturing. Linking heterogeneous lifecycle data is critical to maintain associativity and traceability in a digital thread. Recently, researchers have successfully leveraged ontology models with knowledge graphs in engineering domains for threading different lifecycle data. One of the most successful of such efforts is OntoSTEP which enables the formal capture of information embedded in the STandard for Exchange of Product model data (STEP) data representation, or ISO 10303. Meanwhile, an emerging inspection standard, called the Quality Information Framework (QIF), has garnered significant attention as it can bring quality information into the digital thread. Implementing more automated methods for product quality assurance is challenging due to the lack of unified information models from design to inspection. To this end, we propose an approach to fuse as-designed data represented in STEP and as-inspected data represented in QIF in a standards-based digital thread based on ontology with knowledge graphs. Specifically, we present an automated pipeline for generating knowledge graphs representing STEP and QIF data, a mapping implementation to integrate STEP and QIF knowledge graphs, and rules and queries to demonstrate the integration’s potential for better decision making with respect to product quality assurance.

The paper presents the calculation method of the theoretical deviations resulting in the processing of worms screws profiles bottoms using the Vortex threading method. Because the deviation of this size depends on several factors, a program has been developed in order to analyze its size according to the screw constructive parameters but also to the threading device’s constructive characteristics. Also, the working regime used was taken into account. Base on these, the conclusions were drawn regarding these theoretical deviations size and of their influence on the manufacturing process.

Making a macroscale version of a polyrotaxane—a string threaded through multiple rings—is a fairly simple task. Young children commonly craft them, for example, by threading yarn through tube-shape...

Molecular Machines Rotaxanes consist of molecular rings threaded on a central axle. Most approaches to their synthesis have focused on introducing a single ring per axle. Qiu et al. now report a systematic approach to threading up to 10 adjacent rings consecutively. The axle's end groups were constructed to attract free-floating rings when reduced and then to push those rings toward the center upon oxidation. Products of each successive reduction-oxidation cycle were characterized by nuclear magnetic resonance spectroscopy and mass spectrometry. Science , this issue p. [1247][1] [1]: /lookup/doi/10.1126/science.abb3962

We fabricated 4H-SiC ultraviolet avalanche photodiode (APD) arrays and systematically investigated the effect of threading dislocations on electrical and single photon detection characteristics of 4H-SiC APDs. Based on a statistical correlation study of individual device performance and structural defect mapping revealed by molten KOH etching, it is determined with high confidence level that even a single threading dislocation within APD active region would lead to apparent device performance degradation, including increase of dark current near breakdown voltage, premature breakdown and reduction of single photon detection efficiency at fixed dark count rate.

Metamorphic semiconductor devices often utilize compositionally-graded buffer layers for the accommodation of the lattice mismatch with controlled threading dislocation density and residual strain. Linear or step-graded buffers have been used extensively in these applications, but there are indications that sublinear, superlinear, S-graded, or overshoot graded structures could offer advantages in the control of defect densities. In this work we compare linear, step-graded, and nonlinear grading approaches in terms of the resulting strain and dislocations density profiles using a state-of-the-art model for strain relaxation and dislocation dynamics. We find that sublinear grading results in lower surface dislocation densities than either linear or superlinear grading approaches.

We investigated the electrical properties of low-threading-dislocation-density (TDD) GaN crystals grown by Thin-Flux-Growth method in the Na-flux point seed technique for the first time. In addition, we attempted to fabricate GaN crystals with further lower TDD and curvature by using point seeds having a smaller diameter of 250 µm, compared to that from the previous study having a diameter of 1000 µm. As a result, free carrier concentration was 1.1×10^20 cm^(-3) with a resistivity of 9×10^(-4) Ωcm. Moreover, TDD in about 80% of the observation area was on the order of 10^3 cm^(-2) or less, and the radius of curvature of the GaN crystal was over 100 m for both a// and m//, due to the smaller-sized point seeds. These results suggest that low-TDD GaN crystals with low resistivity can be realized with this method, and Na-flux-GaN crystals exhibit a great performance as substrates of power devices.

Wear of form taps in machining of Al-12Si die-cast alloys has been a critical problem for automotive engine manufacturing. Poor quality of formed threads results in high rework cost, and scrap. This research is focused on investigating the wear mechanisms and quantify wear by developing new measurement metrics. In addition, a performance criterion has been proposed to limit machining and evaluate wear on form taps. Abrasion and Adhesion wear mechanisms have caused severe deterioration of lobes on the chamfered length of tap tools during form tapping. A detailed evaluation of the complexity of wear propagation has been presented for critical regions of a lobe in a form tap.

In the manufacturing sector, energy requirements are increasing day by day. Consequently, energy production costs, which are directly affected by economic development, have risen as a result. Pipe threading operations are carried out on special pipe fitting threading machines. In there, threading is achieved with a low number of revolutions and high torque values. In this study, a novel threading machine was produced with an inverter system and inverter outputs controlled by current transformers and ammeters. The process power index (PI) was measured at 25–50 Hz frequencies. A new energy consumption model unlike any in the literature was created for this type of production line and the necessary calculations were made. Results were evaluated based on static response surface methodology (RSM) and experimental design. The effect of the diameter of the pipe contributed 84% and frequency changes 9%, whereas the effect of the product type was approximately 6%.