Low-pass filter without the end effect for estimating transmission characteristics—Simultaneous attaining of the end effect problem and guarantee of the transmission characteristics

A Gaussian filter (GF) is the most commonly used low-pass filter of measuring surface roughness. However, undesirable distortions, called “end effects," occur near the end points of the data ends in GF. The transmission characteristics are one of the most important indicators that show the quality of a filter. Previously, it was only possible to obtain theoretical values for the transmission characteristics of filters whose weights were given by an explicit function. In recent years, it has also become possible to obtain the transmission characteristics of a filter whose weights are given by an implicit function. However, this method has a problem in that the values near the end points of the measurement data become significantly different from each other. The consequence is that end effects may occur in the filter outputs due to side effects of the periodic extension. In the case of a spline filter (SF) applied to open profiles, the transmission characteristics of a periodic SF with an end effect can be obtained uniquely. However, the transmission characteristics of a nonperiodic SF, which has no end effect, cannot be uniquely obtained. This results in a trade-off between the two states: end effects exist in a filter whose transmission characteristics can be obtained, and the transmission characteristics of a filter without end effects cannot be uniquely obtained. To address this problem, we propose a method for the GF processing that uses shearing, point symmetric extension, and periodic extension, and produces no end effect but allows the transmission characteristics to be obtained. Previously, there was a problem with the proposed method in that the rationale was unclear regarding how to determine the reference points for point symmetric extension. We resolved this and optimized the reference points. As a result, the proposed method was shown to be successful in not only resolving the end effects in the GF, but also obtaining the transmission characteristics.     

Investigation of the effect of machining parameters on the surface quality of machined brass (60/40) in CNC end milling—ANFIS modeling

Brass and brass alloys are widely employed industrial materials because of their excellent characteristics such as high corrosion resistance, non-magnetism, and good machinability. Surface quality plays a very important role in the performance of milled products, as good surface quality can significantly improve fatigue strength, corrosion resistance, or creep life. Surface roughness (Ra) is one of the most important factors for evaluating surface quality during the finishing process. The quality of surface affects the functional characteristics of the workpiece, including fatigue, corrosion, fracture resistance, and surface friction. Furthermore, surface roughness is among the most critical constraints in cutting parameter selection in manufacturing process planning. In this paper, the adaptive neuro-fuzzy inference system (ANFIS) was used to predict the surface roughness in computer numerical control (CNC) end milling. Spindle speed, feed rate, and depth of cut were the predictor variables. Experimental validation runs were conducted to validate the ANFIS model. The predicted surface roughness was compared with measured data, and the maximum prediction error for surface roughness was 6.25 %, while the average prediction error was 2.75 %.     

structures of various macerals,the h

rinite needs high thermal energy to produce major gas hydrocarbons.The pyrolysis of exinite could effectively produce hydrocarbons.It is considered as a good hydrocarbon source.Although hydrocarbons could be limitedly generated through the pyrolysis of inertinite,they are relatively stable and poorly affected by the thermal degradation.Thus,th     

Enhanced geometric precision of non-contact,conformal 3D printing via “error-transferred” towards jetting-direction

Conformal inkjet printing with multi-axis linkage motion platform that enables the fabrication of a variety of curved electronics has drawn great attention recently. However, the geometric precision of inkjet printing on arbitrary surface is a long-term obstacle for the fabrication of curved electronics. Herein, we propose a precision-enhanced method for non-contact, conformal 3D printing based on the unique characteristics of the relatively large error tolerance along jetting-direction. The in-surface geometric precision is enhanced by sacrificing the precision along the jetting-direction, namely “error-transferred” algorithm, after establishing a kinematics model of conformal printer to digitize the movements and error conditions of the axes. The precision-enhanced method has finally been verified by carrying out a corresponding geometric error comparison via simulations and linear-array printing experiments. And the average reduction in geometric error turns out to 20.85% and 12.28% in simulation and experiment results, respectively. We envision that this precision-enhanced method could also be applicable and can be extended to other non-contact process methods such as laser processing, plasma etching, and so on.     

On the Possibility of Experimental Study of Rare η-, ω-, and η"-Meson Decays with the U-70 Accelerator

We consider potential experiments at the U-70 accelerator (Institute for High Energy Physics, Protvino) on the search and study of rare neutral -, -, and "-meson decays that are critical for the modern theory, at a qualitatively new level of statistical accuracy. A special setup with the use of meson tagging and electromagnetic calorimetry on PbWO₄crystals is offered for this experiment. The neural net approach was invoked at the stage of data processing. The Monte Carlo simulation of the experiment demonstrated its high sensitivity to rare-decay detection, which far exceeds the existing world results.     

Studies of the growth, evolution, and self-aggregation of β-amyloid fibrils using tapping-mode atomic force microscopy

Amyloid peptide (Aβ) is the major protein component of plaques found in Alzheimer's disease, and the aggregation of Aβ into oligomeric and fibrillic assemblies has been shown to be an early event of the disease pathway. Visualization of the progressive evolution of nanoscale changes in the morphology of Aβ oligomeric assemblies and amyloid fibrils has been accomplished ex situ using atomic force microscopy (AFM) in ambient conditions. In this report, the size and the shape of amyloid β(1-40) fibrils, as well as the secondary organization into aggregate structures were monitored at different intervals over a period of 5 months. Characterizations with tapping-mode AFM serve to minimize the strong adhesive forces between the probe and the sample to prevent damage or displacement of fragile fibrils. The early stages of Aβ growth showed a predominance of spherical seed structures, oligomeric assemblies, and protofibrils; however the size and density of fibrils progressively increased with time. Within a few days of incubation, linear assemblies and fibrils became apparent. Over extended time scales of up to 5 months, the fibrils formed dense ensembles spanning lengths of several microns, which exhibit interesting changes due to self-organization of the fibrils into bundles or tangles. Detailed characterization of the Aβ assembly process at the nanoscale will help elucidate the role of Aβ in the pathology of Alzheimer's disease.     

Research on the modeling of burr formation process in micro-ball end milling operation on Ti–6Al–4V

Burrs generated along the finished edges and surfaces in micro-milling operation have significant impact on the surface quality and operational performance of the finished parts and microstructures. In order to obtain a better recognition of burr generation process, 3-dimensional micro-ball end milling operation FEM models on Ti–6Al–4V have been established. As a result, a newfound type of burr lying on the slot base has been detected. According to their generating locations, burrs discovered in the simulation are classified into four types: entrance burr, exit burr, top burr, and slot base burr. Their formation processes, especially the generation procedure of slot base burr, are carefully investigated and analyzed. Furthermore, the correlation between cutting parameters and top burr sizes in micro-ball end milling is investigated. At last, effective validation experiments for the proposed model are conducted and good agreements are achieved in the morphologies of burrs between the experiments and simulations. It can be concluded that the adoption of a small ratio of axial depth of cut to the mill radius has a significant effect in the reduction of top burr generation in micro-ball end milling operation.     

Estimate of the lower-limb-specific muscle parameters during bipedal walking for humans, apes and early hominids with the implications for the evolution of body proportion

Modem human has different body proportion from early hominids and great apes. Comparing with others, in general, modem human adults have relatively long lower limb and heavier body weight. Since the lower limbs provide support to the whole body and play an important role in walking, it is proposed that the ratio of the lower limb to the whole body for modem human could be beneficial to bipedal walking. This study tried to estimate the muscle parameters of the lower limb in walking for the subjects with various body proportions. Using a simplified musculoskeletal model, some muscle parameters of the lower limb, e.g. muscle force, stress, work and power, were estimated for modem human adult, child, AL 288-1 （the fossil specimens of Australopithecus afarensis, 3.18 million years old） and apes. The results show that with the body proportion modem human adult spends less muscle work and power in walking than other subjects. The results imply that using the cost of transport （ i. e. the muscle work of the lower limb per unit of displacement） as the criteria, the early hominids, if their body proportions were structurally similar to AL 288-1, could evolve towards what modem human adult looks like, in order to save energy during bipedal walking.     

Investigating the parameters of electron beams in the presence of ion compensation of the charge using the “hole chamber” method

The parameters of electron beams produced by a hollow-anode gas-discharge electron gun based on a glow discharge and operated in an ion focusing mode at medium and low vacuum have been investigated. The “hole chamber” method is proposed. Using a device based on this method, it is possible to measure the electron beam parameters with a high efficiency under conditions of ion focusing when testing the performance of the gas-discharge electron gun in technological processes.     

Modernization of the Duoplasmatron of the И-2 Linear Accelerator

A modified ion source of the duoplasmatron type used in the -2 linear accelerator for generating a proton beam is described. Improving the designs of the electrodes, the magnetic circuit, the gas-supply channel, and the electromagnetic valve has made it possible to considerably increase the service life of the source (up to 10⁷ pulses), to reduce the consumption of hydrogen (up to 10 cm³/h at a pulse repetition rate of 1 Hz), and to increase the stability and reliability of the source operation in the regime of everyday service of the linear accelerator in applied research as an injector of the ITEP U-10 proton synchrotron.     

Electro-and photochemical studies of gold (Ⅲ) bromide towards a novel laser-based method of gold patterning

In this report, we demonstrate a novel technique for the microscopic patterning of gold by combining the photoreduction of Au~ⅢBr₄^-to Au~ⅠBr₂^-and the electrochemical reduction of Au~ⅠBr₂^-to elemental gold in a single step within solution. While mask-based methods have been the norm for electroplating, the adoption of direct laser writing for flexible, real-time patterning has not been widespread. Through irradiation using a 405 nm...     

Frequency–spectrum characteristics of force in end milling with tool wear and eccentricity

The effects of chip load, tool wear, and tool eccentricity on milling force are similar; in order to distinguish them from each other, the spectral characteristics of milling force for four flute end mills was studied. With simplified milling force model, the calculation expression of instantaneous milling force under tool eccentricity was derived based on the 2D geometry of tool cutting into workpiece. Using simulation methods, the amplitude spectra of milling forces under neither wear nor eccentricity, only eccentricity, both wear and eccentricity, and the every phase spectrum of force caused only by wear of one tooth were analyzed. The analysis results showed that the basic and third harmonic amplitudes of spindle frequency were linear only with eccentric distance, the fourth harmonic amplitude was linear only with feed, the second harmonic component was in relationship only with tool wear, and harmonics with same frequency caused by wear of different teeth were in phase or out of phase. Then corresponding milling experiments were done, the relations between experimental harmonic amplitudes of force and milling parameters were analyzed, and were found being in good agreement with above simulation results. These indicate that amplitudes of these harmonics could be taken as indices in recognizing eccentricity, wear, and chip load, respectively, and their variations contain in-process information of tool wear. This study proposes a new idea of identifying tool eccentricity and wear with force itself.     

The biomechanics of plate fixation of periprosthetic femoral fractures near the tip of a total hip implant: cables, screws, or both?

Femoral shaft fractures after total hip arthroplasty (THA) remain a serious problem, since there is no optimal surgical repair method. Virtually all studies that examined surgical repair methods have done so clinically or experimentally. The present study assessed injury patterns computationally by developing three-dimensional (3D) finite element (FE) models that were validated experimentally. The investigation evaluated three different constructs for the fixation of Vancouver B1 periprosthetic femoral shaft fractures following THA. Experimentally, three bone plate repair methods were applied to a synthetic femur with a 5 mm fracture gap near the tip of a total hip implant. Repair methods were identical distal to the fracture gap, but used cables only (construct A), screws only (construct B), or cables plus screws (construct C) proximal to the fracture gap. Specimens were oriented in 15 degrees adduction to simulate the single-legged stance phase of walking, subjected to 1000 N of axial force, and instrumented with strain gauges. Computationally, a linearly elastic and isotropic 3D FE model was developed to mimic experiments. Results showed excellent agreement between experimental and FE strains, yielding a Pearson linearity coefficient, R2, of 0.92 and a slope for the line of best data fit of 1.06. FE-computed axial stiffnesses were 768 N/mm (construct A), 1023 N/mm (construct B), and 1102 N/mm (construct C). FE surfaces stress maps for cortical bone showed Von Mises stresses, excluding peaks, of 0-8 MPa (construct A), 0-15 MPa (construct B), and 0-20 MPa (construct C). Cables absorbed the majority of load, followed by the plates and then the screws. Construct A yielded peak stress at one of the empty holes in the plate. Constructs B and C had similar bone stress patterns, and can achieve optimal fixation.     

Dimensioning of the intermediate states of the machined phases “DISMP” approach

In manufacturing practice for each machining operation, transfer techniques are extensively used for the allocation of manufacturing specification tolerance type and value. This paper focuses more on tolerance type which is the basis for a coherent and complete tolerancing process. We developed an algorithmic method called “DISMP” in order to generate the necessary types of manufacturing specifications that guarantee the respect of the functional requirements. A geometric variation model, based on the invariants degrees of freedom (DOFs) of the datum reference frames (DRF) and the toleranced surfaces serves to specify the two extremities of the tolerance chain. The identification of the controlled DOFs (Cont-DOFs) of the positioning reference frames in each machining phases and also the constrained DOFs (Cons-DOFs) of each machined surface contributes to the development of the way linking between the functional toleranced surface and its functional DRF. To generate the appropriate manufacturing geometric specifications, our method can be divided in five steps. We started by the translation of the ISO functional specification using the topologically and technologically related surfaces rules “TTRS” (Step 1: M1). Mapping the manufacturing process (Step 2: M2 and M3) requires the identification of the Cons-DOFs of the machined surfaces and those controlled by the positioning surfaces “Cont-DOFs” in each phase. The search of all chain links, which constitute the tolerance chain, is realized on Step3 (M4 and M5). Then, in step 4 (M6), we generate ISO standardized manufacturing specification. The fifth step (M7) draft technological constraints related to the manufacturing process, i.e., the case where there are inversion in the order between the toleranced surfaces and its DRF. Finally, we present the manufacturing process phases with ISO standards requirements.