Outer Array Research Articles

Optimization of Physical Working Environment Setting to Improve Productivity and Minimize Error by Taguchi and VIKOR Methods

The working environment is one factor that has contribution to the worker's performance, especially for continuous and monotonous works. L9 Taguchi design experiment for inner array is used to design the experiment which was carried out in laboratory whereas L4 is for outer array. Four control variables with three levels of each are used to get the optimal combination of working environment setting. Four responses are also measured to know the effect of four control factors. Results shown that by using ANOVA, the effect of illumination, temperature, and instrumental music to the number of ouput, number of error, and rating perceived discomfort is significant with the total variance explained of 54,67%, 60,67%, and 75,22% respectively. By using VIKOR method, it yields the optimal combination of experiment 66 with the setting condition of A3-B2-C1-D3. The illumination is 325-350 lux, temperature is 240-260C, fast category of instrumental music, and 70-80 dB for intensity of the music being played.

DOA and Polarization Estimation Based on Sparse COLD Array

Direction of arrival (DOA) ambiguity influences the performance of array signal processing. To address this problem, a DOA and polarization estimation method is proposed in this paper. Based on sparse uniform concentric semi-circular array consisting of concentred orthogonal loop and dipole pairs, the actual array steering vector can be transformed into a virtual one without additional computation. By applying dot division and dot product operation to outer and inner circular ring array spatial steering vectors, two new spatial steering vectors of arrays whose inter-element spacing are less and much larger than half wavelength are obtained respectively, the cyclic phase ambiguity is disambiguated effectively. In the proposed algorithm, all the array elements (actual and virtual) contribute toward the derivation of both the coarse estimations and the fine estimations, thereby achieving full exploitation of the entire physical aperture, the estimation precision is herein improved.

Taguchi optimization approach for production of activated carbon from phosphoric acid impregnated palm kernel shell by microwave heating

Taguchi method was applied to investigate the optimal operating conditions in the preparation of activated carbon using palm kernel shell with quadruple control factors: irradiation time, microwave power, concentration of phosphoric acid as impregnation substance and impregnation ratio between acid and palm kernel shell. The best combination of the control factors as obtained by applying Taguchi method was microwave power of 800 W, irradiation time of 17 min, impregnation ratio of 2, and acid concentration of 85%. The noise factor (particle size of raw material) was considered in a separate outer array, which had no effect on the quality of the activated carbon as confirmed by t-test. Activated carbon prepared at optimum combination of control factors had high BET surface area of 1473.55 m² g−1 and high porosity. The adsorption equilibrium and kinetic data can satisfactorily be described by the Langmuir isotherm and a pseudo-second-order kinetic model, respectively. The maximum methylene blue adsorbing capacity suggested by the Langmuir model was 1000 mg g−1.

Two-dimensional magnetohydrodynamic studies of implosion modes of nested wire array z-pinches

Implosion dynamics of nested wire arrays in (r, θ) geometry was studied with two-dimensional magnetohydrodynamic (2D MHD) simulations. Three different implosion modes are obtained by just changing the wire number of the outer array, when the other conditions, such as the initial radius, length, mass of each array, the wire number of the inner array, and the discharge voltage waveform, are fixed. Simulation results show that the effect of discrete wires, which cannot be described by the thin shell inductive model, will influence the distribution of current between the outer and inner arrays at the early stage, and the discrepancy between results from MHD and thin shell model increases with the interwire gap of the outer array.

Evaluating the Effect of Main Factors in Determining Speed Bump Location Based on Taguchi Design of Experiments

Use of speed bumps as a traffic-calming technique is a key issue to a safe and smooth traffic flow. Lack of consideration on finding the best location for speed bump installation before stop points, such as traffic junctions, has provided the motivation to conduct this study. This paper investigates the influence of some main factors on determining bump location and to optimize the distance from bump to stop point in order to obtain the minimum speed at this point. A robust design was used whereby the effect of environmental noises on the parameters was investigated using the Taguchi design of experiments. A 2-level L8 inner array and an L4 outer array design is used to evaluate and analyze the results. The results suggested that the linear models effectively explain the performance indicators within the ranges of the factors. It can be concluded that the optimum setting suggested is at the most influential levels of the design parameters which yields a robust and insensitive design for speed bump installation after considering the effect of environmental noises. The car speed before bump has the greatest influence and also the most robust factor in terms of signal-to-noise ratio and mean analysis.

Colocation and role of polyphosphates and alkaline phosphatase in apatite biomineralization of elasmobranch tesserae

Elasmobranchs (e.g. sharks and rays), like all fishes, grow continuously throughout life. Unlike other vertebrates, their skeletons are primarily cartilaginous, comprising a hyaline cartilage-like core, stiffened by a thin outer array of mineralized, abutting and interconnected tiles called tesserae. Tesserae bear active mineralization fronts at all margins and the tesseral layer is thin enough to section without decalcifying, making this a tractable but largely unexamined system for investigating controlled apatite mineralization, while also offering a potential analog for endochondral ossification. The chemical mechanism for tesserae mineralization has not been described, but has been previously attributed to spherical precursors, and alkaline phosphatase (ALP) activity. Here, we use a variety of techniques to elucidate the involvement of phosphorus-containing precursors in the formation of tesserae at their mineralization fronts. Using Raman spectroscopy, fluorescence microscopy and histological methods, we demonstrate that ALP activity is located with inorganic phosphate polymers (polyP) at the tessera–uncalcified cartilage interface, suggesting a potential mechanism for regulated mineralization: inorganic phosphate (Pi) can be cleaved from polyP by ALP, thus making Pi locally available for apatite biomineralization. The application of exogenous ALP to tissue cross-sections resulted in the disappearance of polyP and the appearance of Pi in uncalcified cartilage adjacent to mineralization fronts. We propose that elasmobranch skeletal cells control apatite biomineralization by biochemically controlling polyP and ALP production, placement and activity. Previous identification of polyP and ALP shown previously in mammalian calcifying cartilage supports the hypothesis that this mechanism may be a general regulating feature in the mineralization of vertebrate skeletons.

Chinese Puzzle Molecule: A 15 Hydride, 28 Copper Atom Nanoball

AbstractThe syntheses of the first rhombicuboctahedral copper polyhydride complexes [Cu28(H)15(S2CNR)12]PF6 (NR=NnPr2 or aza‐15‐crown‐5) are reported. These complexes were analyzed by single‐crystal X‐ray and one by neutron diffraction. The core of each copper hydride nanoparticle comprises one central interstitial hydride and eight outer‐triangular‐face‐capping hydrides. A further six face‐truncating hydrides form an unprecedented bridge between the inner and outer copper atom arrays. The irregular inner Cu4 tetrahedron is encapsulated within the Cu24 rhombicuboctahedral cage, which is further enclosed by an array of twelve dithiocarbamate ligands that subtends the truncated octahedron of 24 sulfur atoms, which is concentric with the Cu24 rhombicuboctahedron and Cu4 tetrahedron about the innermost hydride. For these compounds, an intriguing, albeit limited, H2 evolution was observed at room temperature, which is accompanied by formation of the known ion [Cu8(H)(S2CNR)6]+ upon exposure of solutions to sunlight, under mild thermolytic conditions, and on reaction with weak (or strong) acids.

Influence of spacing parameters on the wind loading of solar array

Boundary layer wind tunnel tests were conducted to investigate the effects of different spacing parameters on the wind loading of ground and roof mounted solar arrays. On the ground mounted array the effect of lateral and longitudinal spacing between panels was investigated. On the roof mounted array the effect of array perimeter gap from the building edge was investigated. Based on the results obtained, the magnitude of force and moment coefficients on the ground mounted array decreased across panel rows as a result of sheltering effect from the neighboring upwind panels. The largest reduction of wind load coefficients was observed on the second row panels but the amount of reduction dropped quickly afterwards, becoming minimal after the fourth row. It was also observed that panels located in the outer array column could be subjected to relatively higher wind loads compared to panels located in the inner array columns. Increasing the lateral spacing between array columns was observed to have minimal effect on the force and moment coefficients. However, the wind load coefficients increased as the longitudinal spacing between panel rows was increased. The wind load coefficients on the roof mounted array decreased with increasing perimeter gap from the building edge.

Design improvements of a permanent magnet active magnetic refrigerator

A second-generation room-temperature permanent magnet active magnetic regenerator test apparatus using Halbach arrays is described. The magnet arrays consist of three concentric cylinders. Each cylinder is constructed using 12 permanent magnet segments. The inner magnet array is stationary while the intermediate and outer arrays are designed to rotate in opposite directions so as to create a sinusoidal magnetic field waveform with a stationary field direction. The fluid flow system utilizes a novel check valve configuration so that fluid dead volumes are minimized. The system construction is modular to allow for quick replacement of material or system components. Fringing fields near the outer and inner diameters of the arrays are found to create large forces between arrays leading to large torques. Test results using 650 g of gadolinium spheres produce a no-load temperature span of 33 K at 0.8 Hz.

Dosimetric Comparison of 3-Dimensional Planning Techniques Using an Intravaginal Multichannel Balloon Applicator for High-Dose-Rate Gynecologic Brachytherapy

To study the dosimetric differences of various channel combinations of the Capri vaginal applicator. The Capri consists of a single central channel (R1), an inner array of 6 channels (R2), and an outer array of 6 channels (R3). Three-dimensional plans were simulated for 6 channel arrangements (R1, R2, R12, R13, R23, and R123). Treatment plans were optimized to the applicator surface or 5-mm depth while minimizing dose to organs at risk (OARs: bladder, rectum, sigmoid, and urethra). The clinical target volume (CTV) was defined as a 5-mm circumferential shell extending 4 cm in length around the applicator. Clinical target volume coverage (Dmean, D90, V100, and V150) and OAR doses (D0.1 cm3, D1 cm3, D2 cm3, and Dmean) were compared. A comparison between the Capri (R123) and a conventional single-channel applicator was also done. Statistical significance (P value<.05) was evaluated with a 2-tailed t test. When prescribing to 5-mm depth, CTV coverage using all 13 channels (R123) versus a single channel (R1) was similar; however, when prescribing to the surface there were differences (P<.0001) in all CTV metrics except for the V150. The R1 plans had higher doses to all OARs compared with R123 plans (P<.007). Doses to OARs were not significantly different between R23 and R123 plans (P=.05-.95), and CTV coverage differences were on the order of 1%. Capri R123 plans provided slightly lower CTV D90 and Dmean but equivalent OAR doses with smaller standard deviations compared with conventional cylinder plans for both prescriptions. The Capri multichannel applicator provides equivalent target coverage at 5-mm depth, with significantly reduced dose to OARs relative to using a single channel. Optimal plans can be achieved using R12 (lowest V150) or R123 or R23 (lowest OAR doses).

Experimental validation of sound field control with a circular double-layer array of loudspeakers

This paper is concerned with experimental validation of a recently proposed method of controlling sound fields with a circular double-layer array of loudspeakers [Chang and Jacobsen, J. Acoust. Soc. Am. 131(6), 4518-4525 (2012)]. The double-layer of loudspeakers is realized with 20 pairs of closed-box loudspeakers mounted back-to-back. Source strengths are obtained with several solution methods by modeling loudspeakers as a weighted combination of monopoles and dipoles. Sound pressure levels of the controlled sound fields are measured inside and outside the array in an anechoic room, and performance indices are calculated. The experimental results show that a method of combining pure contrast maximization with a pressure matching technique provides only a small error in the listening zone between the desired and the reproduced fields, and at the same time reduces the sound level in the quiet zone as expected in the simulation studies well above the spatial Nyquist frequency except at a few frequencies. It is also shown that errors in the positions of the loudspeakers can be critical to the results at frequencies where the distance between the inner and the outer array is close to half a wavelength.

An orthogonal arrays approach to robust parameter designs methodology

Robust parameter design methodology was originally introduced by Taguchi [14] as an engineering methodology for quality improvement of products and processes. A robust design of a system is one in which two different types of factors are varied; control factors and noise factors. Control factors are variables with levels that are adjustable, whereas noise factors are variables with levels that are hard or impossible to control during normal conditions, such as environmental conditions and raw-material properties. Robust parameter design aims at the reduction of process variation by properly selecting the levels of control factors so that the process becomes insensitive to changes in noise factors. Taguchi [1415] proposed the use of crossed arrays (inner–outer arrays) for robust parameter design. A crossed array is the cross-product of an orthogonal array (OA) involving control factors (inner array) and an OA involving noise factors (outer array). Objecting to the run size and the flexibility of crossed arrays, several authors combined control and noise factors in a single design matrix, which is called a combined array, instead of crossed arrays. In this framework, we present the use of OAs in Taguchi's methodology as a useful tool for designing robust parameter designs with economical run size.

Experimental study on current division of nested wire array Z pinches

The current division between the inner and the outer arrays is one of the key factors that impact the implosion dynamics and modes of nested wire array. This paper presents the first quantitative measurements of current division for nested wire array Z pinch on the Qiang Guang-I pulsed power facility. In experiments, the nested wire arrays, made of 3.8 μm-diameter tungsten wires, were 20 mm in height and 8 mm/16 mm in diameter for inner/outer array. Measurements for loads consisting of 42/21 wires in inner/outer array were compared with that of 21/42 in inner/outer array. Data of current versus time at various radial positions were obtained using magnetic probes until 20 ns before the current peak. Results show that the currents in inner and outer arrays increase during the rise of the driving current, the proportion of current in outer array decreases and that in inner array increases, while the current in outer array, for loads with 21/42 wires in inner/outer array, was larger than those with 42/21 wires in inner/outer array.

Optimisation of welding process parameters for distortion control with Taguchi approach

Weld distortion minimisation in Tungsten Inert Gas (TIG) welding process is achieved by using Taguchi approach. The transverse distortion of TIG welding process was evaluated using weld current, root gap, Argon gas flow rate and the weld speed as the main parameters using an L8 orthogonal outer array. Three noise factors were accommodated in L4 array. Analysis of Variance (ANOVA) is applied for the optimisation, first for effectiveness then for mean and finally for variation. From these experiments, it was found that the factors like weld current, weld speed and root gap have major contribution in controlling both mean and variation of weld distortion. The estimated optimum distortion is two degrees.

Demonstration of Radiation Pulse-Shaping Capabilities Using Nested Conical Wire-Array $Z$-Pinches

We present data from experiments using nested wire-array Z -pinches where the wires of one of the arrays (the outer or inner array) are inclined to produce a cone. The use of these nested conical arrays can potentially provide a valuable tool in X-ray radiation pulse shaping for Z-pinch-driven high-yield inertial-confinement-fusion schemes. Conical nested arrays can produce a zippered implosion which broadens the main radiation pulse and, possibly, the pulse associated with the interaction of the two arrays. Results from experiments at current levels of 1 MA (240 ns) and 18 MA (100 ns) are presented and compared. Experiments at 1 MA with a conical outer array indicate broadening of the full-width at half-maximum of the main stagnation radiation pulse, with results at 20 MA showing a similar result. Conical inner arrays do not broaden the main radiation pulse because a longer inner array ablation time offsets the earlier interaction time of the outer array with the inner array. Although array dynamics data suggest that a conical inner or outer array can potentially provide control of the interaction radiation pulse, this was not observed. Observations are consistent with a wire-array trajectory model incorporating outer and inner array ablation, snowplow physics, and a simplified array interaction model.

Perceptual grouping allows for attention to cover noncontiguous locations and suppress capture from nearby locations.

A salient stimulus may interrupt visual search because of attentional capture. It has been shown that attentional capture occurs with a wide, but not with a small attentional window. We tested the hypothesis that capture depends more strongly on the shape of the attentional window than on its size. Search elements were arranged in two nested rings. The ring containing the search target remained fixed, while a salient color singleton occurred either in the same or in the other ring. We observed that color singletons only disrupted search when shown in the same ring as the search target. It is important to note that, when focusing on the outer array, which presumably required a larger attentional window, singletons on the inner array did not capture attention. In contrast to the original attentional window hypothesis, our results show that attentional capture does not always occur with a large attentional window. Rather, attention can be flexibly allocated to the set of relevant stimulus locations and attentional capture is confined to the attended locations. Further experiments showed that attention was allocated to search elements that were perceptually grouped into "whole" or "Gestalt"-like objects, which prevented attentional capture from nearby locations. However, when attention was allocated to noncontiguous locations that did not form a perceptual Gestalt, nearby locations elicited attentional capture. Perceptual grouping could be based on a combination of color and position, but not on color alone. Thus, the allocation of attention to Gestalt-like objects that were jointly defined by similarity and proximity prevented attentional capture from nearby locations.

Shock model description of the interaction radiation pulse in nested wire array z-pinches

Bow shock structures are observed in a nested wire array z-pinch as ablation streams from the outer array pass the inner array. The jump in plasma conditions across these shocks results in an enhancement of snowplow emission from the imploding plasma piston. Results from a snowplow model modified to account for the shock jumps are discussed and compared to experimental data from MAGPIE. Magnetohydrodynamic simulations indicate that this is the primary heating mechanism responsible for the interaction pulse recorded on the Z generator, which is required for pulse shaping for inertial confinement fusion.

Tolerance range section of topologically optimized structure using combined array design of experiments approach

Topology optimization is a popular method to optimize the material for structural components. For minimum compliance problem, the effectiveness of the obtained topology is characterized by its compliance value. Here, compliance value depends on many factors. Due to uncertainties in these factors, desired compliance value is difficult to achieve. The sensitivities of these factors have already been investigated by researchers. Present work focuses on the selection and the significance of tolerance of these factors. The tolerance of input factors like applied force, volume fraction, aspect ratio of material domain and modulus of elasticity are selected to investigate the effect on compliance. To select tolerance range, the concept of inner and outer orthogonal arrays proposed by Taguchi is employed along with solid isotropic microstructure with penalization method of topology optimization. Different tolerance ranges are selected for each factor and tolerance combinations are generated using inner array. Thereafter outer array is used to create replications of a particular combination. For each replicate, compliance value is simulated using solid isotropic microstructure with penalization method. Based on statistical analysis of obtained values, significant factors are identified and optimal tolerance ranges are selected. In similar way, maximum deflection values are also simulated for analysis. Proposed methodology is applied on four different benchmark problems. The presented approach provides the effect of each possible set of tolerance on performance functions, which are compliance and deflection values. This work will be helpful to designers to select optimum tolerance of factors to achieve desired compliance value and performance for a topologically optimized structure prior to manufacturing in the realistic environment.

Study of the precursor and non-precursor implosion regimes in wire array Z-pinches

Star-like and closely spaced nested wire array configurations were investigated in precursor and non-precursor implosions. Closely spaced nested cylindrical arrays have inner and outer arrays with equal wire numbers, and inner and outer wires aligned to each other. The gap between the outer and inner wires is not more than 1 mm. Calculation of magnetic fields shows that the small gap results in a reversed, outward j × B force on the inner wires. Closely spaced arrays of 6–16 wires with outer diameter of 16 mm and with gaps of ΔR = 0.25–1 mm were tested. 6–8-wire arrays with a gap of ΔR = 0.4–1 mm imploded without precursor, but precursor was present in loads with 12–16 wires and ΔR = 0.25–1 mm. Implosion dynamics of closely spaced arrays was similar to that of star-like arrays. Implosion time was found to decrease with decreased wire numbers. Star array configurations were designed with a numerical scheme to implode with or without precursor. The lack of precursor resulted in a marginal improvement in total x-ray yield and power, and up to 20% increase in Al K-shell yield. The Al K-shell radiated energy was found to increase with decreasing the number of arrays in closely spaced and star-like wire arrays.

SU-D-213AB-02: Optimal Design of Multichannel Vaginal Cylinder Applicators for High Dose Rate Brachytherapy.

To determine the optimal location of catheters in multichannel vaginal applicators to appropriately cover the vaginal cuff target and minimize dose to the organs at risk (OARs) and hot spots in the target. A new multichannel vaginal applicator with a diameter of 30 mmconsists of a single central catheter and an outer array of eight catheters. A total of 20 plans were generated from 5 patients by using different outer catheter locations at r = 4, 8, and 12 mm. The target was defined as a 5 mmcircumferential shell extending 4 cm in length around the applicator, excluding the bladder, rectum, and bowel. An inverse planning simulated annealing algorithm and graphical optimization was applied to ensure the prescription dose (7.0 Gy per fraction) covered >97% of the target and minimized dose to the OARs. Target coverage (D90 and V100), hot spots (V150 and V200), and OAR doses (D0.1cc, D1cc, and D2cc) from the various catheter placements were compared to single catheter plans. By study design all plans had the same target coverage D90 (105.0- 108.3%) and V100 (97.1-97.2%). The V150 and V200 were 16.1% and 3.4% (r=0mm), 17.3% and 4.2% (r=4mm), 20.1% and 2.2% (r=8mm), and 30.1% and 6.0% (r=12mm). The DO.1cc to the OARs from the various catheter placements at r = 4, 8, and 12 mm was reduced by 4.0%, 8.6%, 11.9% (bladder), 7.4%, 13.2%, and 17.4% (rectum), when compared to the central catheter plans. Multichannel vaginal applicators provide better dosimetry than single channel applicator. The catheter array located closest to the applicator surface most significantly reduces dose tothe OARs at the expense of larger hot spots in the target. The array in the middle of the applicator radius provides significantly decreased dose to the OARs and gave relatively smaller hot spots.