Diamond-shaped Research Articles

Numerical Investigation of Thermal Hydraulic Performance of Printed Circuit Heat Exchanger of Periodic Diamond Channel Shape

One of the most recently important heat exchangers is the Printed circuit heat exchanger especially in the nuclear power plant and aerospace applications due to its very compact geometry and small print foot. This paper presents a 3D numerical investigation on the thermo-hydraulic performance of PCHE with new non-uniform channel design configuration. The new channel design is a rectangular cross section with repeated converging diverging sections or periodic diamond shape. The influence of three design parameters on the heat exchanger performance was studied and optimized, pitch length (p), length ratio (β) and the converging diverging angle (α). The computational models investigated in this study based on the operating conditions of the intermediate heat exchanger of very high temperature gas cooled reactor with helium as the working fluid under operating pressure of 3Mpa and inlet temperature of 800 K. The Reynolds number varied from 200 to 2000. Different Pitch lengths were used (1.59, 3.18, 6.36, and 12.73) mm, and different C-D angle (0, 4.5, 6, 7.5, 9, 10.5 and 12) and also different length ratios were used (0.2, 0.25 and 0.333). Three performance parameters were studied the Nusselt number, friction factor and the overall performance evaluation factor. Results show that the thermal performance enhanced with decreasing the pitch length and with increasing C-D angle and it was shown that this enhancement was found only at high Reynolds number above 1400. The best performance obtained at p=3.18, α=6 and β=0.25 based on the overall evaluation performance.

Electronic structure exploration of the fluxional B4 subunit of B13+ tri-spoke wheel for understating its rotor action

B13+ cluster is a unique nano-scale tri-spoke wheel which exhibits rotor action. This rotor action is associated with the interconversion between two closely lying states - the minimum energy ground state (GS) and a closely lying transition state (TS) of this planar cluster in which a B4 subunit successively transforms from the square shape in GS to the diamond shape in TS. In the present study, the square to diamond fluxional interconversion of the B4 subunit has been explored through electronic structural analysis including AdNDP, LOL and AIM analysis. Nucleus independent chemical shift (NICS) study has also been carried out for both the parent cluster and the B4 unit to understand the inter-relationship in the aromatic character of these clusters. The electronic scale origin of the fluxional character of the B4 cluster has been explored and its connection with the diamond-square-diamond (DSD) mechanism can be foreseen.

Evaluation of the Association of Oral Stereognosis with Malocclusion in Children.

Aim and objectiveTo evaluate the association between oral stereognosis with malocclusion in children.Materials and methodsStereognostic investigation was made with a set of seven different geometric configurations (circle, square, triangle, star, clover, diamond, and heart shapes) cut out from fresh, raw carrots using preformed iron molds. Any five of the seven geometric forms were randomly placed inside the mouth on the dorsum of the tongue by the investigator with the subject's eyes closed. A minimum of three shapes correctly identified out of the five offered to each child was considered as an indicator of the adequate stereognostic ability of that particular child.ResultsAmong the children under Index of Orthodontic Treatment Needs (IOTN) grade I group, 82.4% of children came under the positive response group. Among IOTN grades II, III, and IV, the percentages of children with positive responses were 72.1%, 58.1%, and 18.8%, respectively. There is a statistically significant (p < 0.001) decrease in positive response with increasing IOTN grades.ConclusionThe observations from the present study show that there is altered oral sensory perception in children graded as with malocclusion according to the index used and belonging to the age group selected in the study.Clinical significanceSensory and motor components of the orofacial region, like any other part of the human body, are inseparable in their structure and function, the association between orofacial growth and development and sensory maturation cannot be overlooked.How to cite this articleJanardhanan R, Soman A, George S, et al. Evaluation of the Association of Oral Stereognosis with Malocclusion in Children. Int J Clin Pediatr Dent 2021;14(S-1):S18–S21.

Care Triangle or Care Diamond? The Case of Childcare and Eldercare in Serbia

Overall changes in political, social and economic spheres in Serbia, along with ongoing demographic processes, have affected various policies and all aspects of people’s lives, including system(s) of care. While care became an important analytical concept and category of social policy analysis internationally, it has not been systematically applied in the analysis of the Serbian welfare state. Incorporation of care in welfare state analysis is much needed as its organisation in the national context reveals a lot about the nature of the welfare state, changes in its socio-institutional arrangements and, most importantly, the effects of provision. This article thus aims to outline the evolution of childcare and eldercare policies in Serbia over the last decade, employing the concept of the care diamond developed by Shahra Razavi, which allows examining the “architecture” through which the care is provided: families/ households, markets, the state and the voluntary sector. By analysing the prevalent care policy “architecture” for children and the elderly in Serbia and the roles of different sectors in that respect, as well as by identifying similarities and differences in the provision of childcare and eldercare in the national context, the article exposes developments and current state in childcare and eldercare provision in Serbia. The analysis indicates the profound role of the informal sphere in both care systems in Serbia, childcare and eldercare. Some differences between the two care domains could also be noted. These relate to the configuration of welfare sectors involved in care provision, revealing the modified shape of the care diamond in the case of childcare. That is, while all four sectors are involved in providing care in the case of eldercare forming an eldercare diamond, this is not the case with childcare. In the latter case, the voluntary, nonprofit sector does not exist as a care provider in Serbia, with childcare “architecture” having a shape of a care triangle. In light of this evidence, the role of families and the voluntary, nonprofit sector should be taken into account in future planning and funding of policies as well as in their implementation. Key words: care, childcare, eldercare, care diamond, policy, provision, Serbia

A comparison of effective dose and risk for different collimation options used in AP shoulder radiography

IntroductionRadiography forms the cornerstone of the evaluation of shoulder disorders. While the benefits of radiography exceed the risks, there continues to be a compelling case for reduction of radiation exposure from diagnostic radiography. The aim of this project was to evaluate the radiation dose and risk for a variety of collimation settings used during anteroposterior (AP) shoulder radiography. MethodsThis was a phantom based study where an ATOM adult dosimetry phantom was loaded with 272 thermoluminescent dosimeters (TLDs). Following loading, the phantom was setup for an AP shoulder X-ray projection with standard 25 × 30 cm rectangular collimation. The phantom was exposed three times and then the TLDs were removed and read. The experiment was repeated using a diamond shaped collimation and rectangular collimation with a minimum field of view to portray only relevant anatomy. Using the TLD dose measurements the effective doses and radiation risks were determined and compared. ResultsAs expected, organs neighbouring the shoulder experienced the highest absorbed doses (greater than 0.01 mGy); these organs included breast, lung and thyroid gland. The effective doses for standard rectangular, small rectangular and diamond collimation were 0.011, 0.008 and 0.016 mSv, respectively. When compared to standard collimation, a small field of view reduced effective dose by 27.3% and when moving to a diamond shape there was a 45.5% increase. The differences are likely driven by differences in the coverage of the radiosensitive lung and breast tissue. ConclusionBy utilising a variety of different collimation settings, effective dose can be reduced. Reducing the radiation dose is both financially beneficial and results in a lower stochastic risk for patients. Image quality must also be considered when choosing different collimation settings. It stands to reason that by reducing the field size, dose will be reduced, and our study has served to quantify the effects in a practical situation. Implications for practiceThe utilisation of smaller/tight collimation is recommended as it offers the lowest dose when compared with other types of collimations. Although well-known this study serves to remind practitioners of the practical importance of collimation and is associated effect on effective dose and risk.

DFT-Based Channel Estimation with Channel Response Mirroring for MIMO OFDM Systems

In this paper, DFT-Based channel estimation with channel response mirroring is proposed and analyzed. In General, pilot symbols for channel estimation in MIMO(Multi-Input Multi-Output) OFDM(Orthogonal Frequency-Division Multiplexing) Systems have a diamond shape in the time-frequency plane. An interpolation technique to estimate the channel response of sub-carriers between reference symbols is needed. Various interpolation techniques such as linear interpolation, low-pass filtering interpolation, cubic interpolation and DFT interpolation are employed to estimate the non-pilot sub-carriers. In this paper, we investigate the conventional DFT-based channel estimation for noise reduction and channel response interpolation. The conventional method has performance degradation by distortion called “edge effect” or “border effect”. In order to mitigate the distortion, we propose an improved DFT-based channel estimation with channel response mirroring. This technique can efficiently mitigate the distortion caused by the DFT of channel response discontinuity. Simulation results show that the proposed method has better performance than the conventional DFT-based channel estimation in terms of MSE.

Controlling macroscale cell alignment in self-organized cell sheets by tuning the microstructure of adhesion-limiting micromesh scaffolds

In vivo tissues, including the cardiac, skeletal muscles, tendon and ligaments display characteristic alignment property which is important for their mechanical property and functionality. Mimicking this alignment property is critical to the realization of physiologically relevant cell sheets for potential application in the regeneration of aligned in vivo tissues. In this study, we aimed to achieve fabrication of aligned cell sheets by harnessing the ability of cells to sense and respond to geometrical cues in their adhesion microenvironment. We demonstrate that macroscale cell alignment in cell sheets formed by C2C12 cells, a mouse myoblast cell line, on adhesion limiting microstructured mesh scaffolds depends on the shape of the scaffold microstructure. Specifically, while square meshes produced cell sheets with random orientation, diamond meshes yielded anisotropic cell sheets with cells aligned uniaxially along the major axis of the diamond shape. Moreover, alignment intensity was found to increase concomitantly with the acuteness of the diamond shape, illustrating alignment dependency on mesh shape anisotropy. Remarkably, myotubes derived from aligned C2C12 cells also displayed a similar alignment trend, demonstrating the robustness of our approach. Taken together, the present study demonstrates the potential to control macroscale cell alignment in self-organized cell sheets by tuning the shape of the scaffold microstructure. Thus, insights from this study could be relevant to the design of instructive scaffolds for fabricating aligned cell sheets for potential application not only in regenerative medicine, but also in developing muscle constructs for toxicity assays.

Structural characteristics of transtensional fault system and its implication for hydrocarbon accumulation in S Block, South Asia area

Transtensional faults are well developed in the S Block of the South Asia area, which have an important impact on the hydrocarbon accumulation. However, the transtensional fault structure is very complex. Based on drilling and seismic data interpretation results, faults are divided into three typical types in the Lower Cretaceous, which can help to understand the complex fault system. The main faults are distributed in the NNW-SSE direction and parallel arrangement with dextral strike-slip shear characteristics, which determines the development of the tectonic belt. The secondary faults are often associated with the main faults, often composed of multiple branch faults. The complexity of the fault system is further aggravated by the small interlayer faults. Based on balanced crosssection technique analysis, the fault evolution has experienced five geological periods, which is closely related to the Indo-Pakistan plate tectonics and the Indus Basin evolution. In the diagonal extension stage of the Late Cretaceous, the fault activity was very strong, which had a significant impact on the tectonic pattern of "horst-graben structures and locally complex faulted blocks" in S Block. It is found that transtensional fault assemblage patterns are regular and diverse. It consists of six kinds of plane assemblage and seven kinds of profile assemblage patterns. Plane assemblage patterns include en echelon, broom, feather, comb, horsetail and diamond shape, while profile assemblage patterns consist of horst-graben faulted type, consequent faulted type, antithetic faulted type, "Y" and reverse "Y" type, "X" type and negative flower type. Different transtensional fault assemblage patterns form various kinds of hydrocarbon trap types, including faulted block, faulted nose, faulted anticline and composite traps. Fault activity and evolution promote the hydrocarbon generation, control the formation of tectonic zones and favorable traps and play an important control role in hydrocarbon migration and accumulation. Therefore, in this study the main exploration and evaluation targets are faulted reservoirs in the study area.

Surface texture of substrates prepared by femtosecond laser for improving the thermal cycle life of TBCs

In this study, a substrate was surface textured using a femtosecond laser to prolong the service life of thermal barrier coatings (TBCs). The selected texture showed linear and diamond shapes. The effect of the texture shape on the thermal shock resistance of the TBCs was investigated by subjecting them to thermal shock cycles. The microstructure and composition of the TBCs were investigated using various characterisation methods. The mechanical properties of the TBCs were measured using the microindentation method. Based on the theory of elastoplastic mechanics, a three-dimensional finite element numerical model was established to analyse the effect of the two textures on the stress distribution of the TBCs. The results revealed that the linear-textured TBCs showed improved stress concentration at the coating interface when the coatings expanded or shrank, which resulted in an improvement in their thermal shock resistance. Therefore, the linear-textured TBCs showed excellent oxidation resistance, fracture toughness, and heat resistance as compared to the diamond-textured TBCs.

Design and fabrication of composite polygonal Fresnel lenses.

High fill factor for Fresnel lens arrays has been achieved with the aid of polygonal lenses. This has been done for both circular trimmed lenses and full polygonal lenses, both of which present some optical drawbacks. The composite polygonal Fresnel lens (CPFL) avoids these issues with its unique design - a radial symmetric Fresnel center filling into a polygon, avoiding any intersecting facets within the lens by introducing fillets. To manufacture the CPFL, diamond shaping is applied to not only meet the strict standards required for optical fabrication but also maneuver around the curvilinear features that cannot be fabricated using conventional turning techniques. As such, direct diamond shaping (DDS) was employed to generate an array of CPFLs on a PMMA substrate. Optical simulation was used to validate the performance of the CPFL before production of the lens array, followed by testing of the fabricated lenses, showing less overall noise with better focus compared to conventional polygonal lenses.

Diamond shaping of blazed gratings on freeform surfaces

The study of spectral signatures of various elements has been enabled with the ability to diffract light using optical gratings, coupled with the ability to control light using lenses and mirrors. As technological devices seek to become more compact while maintaining or increasing operational efficiency, integration of functions becomes necessary to reduce the overall component count. However, due to the lack of axial flexibility, integrated microstructures on complex forms have shown to be challenging to manufacture. Thus, the need for fabrication techniques to be able to produce such microstructures on non-planar surfaces arises. The Continuous Rotating Freeform Shaping (CRFS) algorithm proposed in this paper utilizes the axial flexibility and precision of Ultra-Precision Machining (UPM) to directly fabricate optical quality blazed gratings on complex profiles which can directly be used as mirrors or molds. The developed algorithm not only maintains the tool along the primary profile of the optical surface, but also the rake angle of the tool at every point along the surface for a constant cutting mechanism. This is coupled with a rotation of the tool to maintain the blazed angle across the surface, optimizing the surface for the efficiency of the grating for a specific wavelength. In this paper, the developed algorithm is presented with experimental verifications of the generation of blazed gratings on a high curvature spherical surface and a freeform tri-axial ellipsoidal surface, followed by the corresponding analysis.

Feedback from lateral occipital cortex to V1/V2 triggers object completion: Evidence from functional magnetic resonance imaging and dynamic causal modeling.

Illusory figures demonstrate the visual system's ability to integrate disparate parts into coherent wholes. We probed this object integration process by either presenting an integrated diamond shape or a comparable ungrouped configuration that did not render a complete object. Two tasks were used that either required localization of a target dot (relative to the presented configuration) or discrimination of the dot's luminance. The results showed that only when the configuration was task relevant (in the localization task), performance benefited from the presentation of an integrated object. Concurrent functional magnetic resonance imaging was performed and analyzed using dynamic causal modeling to investigate the (causal) relationship between regions that are associated with illusory figure completion. We found object‐specific feedback connections between the lateral occipital cortex (LOC) and early visual cortex (V1/V2). These modulatory connections persisted across task demands and hemispheres. Our results thus provide direct evidence that interactions between mid‐level and early visual processing regions engage in illusory figure perception. These data suggest that LOC first integrates inputs from multiple neurons in lower‐level cortices, generating a global shape representation while more fine‐graded object details are then determined via feedback to early visual areas, independently of the current task demands.

Numerical investigation of bimaterial interfacial crack with interaction of voids and inclusions using XFEM

This article is presented to investigate the influence of several discontinuity like interfacial-crack, void and inclusion in the bimaterial plate, to analyze the normalized mixed-mode stress intensity factor (NMMSIFs) using XFEM under the uniaxial tensile load with considering the several numerical problems. It is investigated the normalized stress intensity factors (NSIFs) for an isotropic bimaterial plate and NMMSIFs for an isotropic-orthotropic bimaterial plate through varying the single-multi voids/inclusions position while its above, aligned and away from the interfacial edge crack and center crack of the bimaterial plate. It is also analyzed the void/inclusion several shape influence in the bimaterial plate. It is observed higher and fluctuating SIFs obtained with more number of voids/inclusions, influence of elliptical and diamond shape of void/inclusion is higher.

Design and Development of An Instrumented Knee Joint for Quantifying Ligament Displacements

Abstract Recently, robotic assistive leg exoskeletons have gained popularity because an increased number of people crave for powered devices to run faster and longer or carry heavier loads. However, these powered devices have the potential to impair knee ligaments. This work was aimed to develop an instrumented knee joint via rapid prototyping that measures the displacements of the four major knee ligaments—the anterior cruciate ligament (ACL), posterior crucial ligament (PCL), medial collateral ligament (MCL), and lateral collateral ligament (LCL)—to quantify the strain experienced by these ligaments. The knee model consists of a femur, lateral and medial menisci, and a tibia-fibula, which were printed from three dimensional (3D) imaging scans. Nonstretchable cords served as main fiber bundles of the ligaments with their desired stiffnesses provided by springs. The displacement of each cord was obtained via a rotary encoder mechanism, and the leg flexion angle was acquired via a closed-loop four-bar linkage of a diamond shape. The displacements were corroborated by published data, demonstrating the profiles of the displacement curves agreed with known results. The paper shows the feasibility of developing a subject-specific knee joint via rapid prototyping that is capable of quantifying the ligament strain via rapid prototyping.

Impact of Temperature Rise on the Seismic Performance of Concrete-Filled Double Skin Steel Columns with Prismatic Geometry

Abstract This paper studies the impact of temperature rise on the performance of Concrete-Filled Double Skin Tubular Steel Columns with prismatic geometry. In doing so, several columns whose interior cores were square, diamond, and circularly shaped and whose exterior cores were prismatic with a square cross-sectional area that increases with the slope of 2.1 degrees from top to the bottom, were constructed and exposed to the temperatures of 25°C, 250°C, 500°C, and 700°C. Afterward, all column specimens were subjected to cyclic loads adopted from the Applied Technology Council (ATC)-24 loading protocol, which proceeded until the specimens failed to further carry loads. The results indicate that although the failure modes of the columns with an interior core of a square or diamond shape are similar to each other, the columns whose interior cores were circularly shaped experienced more intensive damages compared to the others. The base of the columns was fractured diagonally with a degree of 45 by the temperature of 500°C, but at 700°C, the damages have occurred horizontally at the height of 10 cm from the column base. Moreover, the initial stiffness and ductility ratio of the columns with a diamond-shaped interior core was approximately two times greater than the other columns.

The global profiling of alkaloids in Aconitum stapfianum and analysis of detoxification material basis against Fuzi

Aconitum alkaloids are versatile in chemical structures and are well known for their bioactivity and toxicity. Cases of analogs with closely similar structures or positional isomers are widespread in herbs of the Aconitum genus. It is still challenging to rapidly identify unknown compounds via mass spectrometry, especially positional isomers. Herein, to profile the alkaloids of Aconitum stapfianum that possess bioactivity against intoxication by the lateral root of Aconitum carmichaelii (Fuzi), a strategy was developed by carefully determining the fragmentation pathways of authentic standards. A series of rules was summarized and involved charge site effects, hydrogen bonding effects, competitive channels between charge-remote reactions and charge migration reactions, and fragment patterns exhibiting a “diamond shape”. Accordingly, a total of 124 alkaloids in A. stapfianum were tentatively characterized, including 85 potential new compounds and 24 sets of isomers. On the other hand, to explore the material basis of detoxification, a chemical constituent comparison was made between A. stapfianum and Fuzi, and principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) were performed to identify markers that were different between the two . In total, 25 characteristic markers were identified to discriminate between these two herbal medicines, of which 14 compounds were specific for A. stapfianum and most of them were characteristic for a para-substituted benzoic acid ester at C-14.

Cooperative Control of Manipulator and Human Operator for Direct Teaching

A cooperative control of a manipulator and a human operator has been proposed for an efficient direct teaching operation in this research. The main goal is making the operator be convenient and relaxed when he is operating the manipulator for a direct teaching. The proposed control strategy has two layers: In the first layer, human motion estimator (HME) has been designed to estimate a human intention. The recursive least square method has been utilized for the HME to simultaneously estimate the interaction force and the human arm admittance model. In the second layer, human motion reactor has been designed to keep the human motion intention precisely by a proportional derivative and gravity compensation in real time. Real experiments with a 3-degree of freedom robotic manipulator guided by the human operator have been conducted to draw a diamond shape on a panel. The experimental results demonstrate the effectiveness of the proposed cooperative control strategy.

Anomalous anisotropy of the lower critical field and Meissner effect in UTe2

We report on low temperature susceptibility and magnetization measurements made on single crystals of the recently discovered heavy-fermion superconductor UTe$_2$ and compare the results with the two ambient pressure ferromagnetic superconductors URhGe and UCoGe. Hysteresis curves in the superconducting phase show a familiar diamond shape superimposed on a large paramagnetic background. The Meissner state was measured by zero field cooling in small fields of a few Oe as well as ac susceptibility measurements in small fields and resulted in 100\% shielding, with a sharp transition. However the field cooling Meissner-Ochsenfeld effect (expulsion of flux) was negligible in fields greater than just a few Oe, but becomes nearly 30\% of the perfect diamagnetic signal when the field was reduced to 0.01~Oe. The critical current due to flux pinning was studied by ac susceptibility techniques. Over the range in fields and temperature of this study, no signature of a ferromagnetic transition could be discerned. The lower critical field $H_{\rm c1}$ has been measured along the three crystalographic axes, and surprisingly, the anisotropy of $H_{\rm c1}$ contradicts that of the upper critical field. We discuss this discrepancy and show that it may provide additional support for a magnetic field-dependent pairing mediated by ferromagnetic fluctuations in UTe$_2$.

Edge-Coupled Parasitic Split Ring Resonator based Metamaterial Inspired Low-Cost Diamond Shaped Fractal Antenna for Multiband Wireless Applications

ABSTRACT The metamaterial inspired low-cost diamond-shaped fractal antenna (DSFA) based on edge-coupled (EC) parasitic split ring resonator (SRR) for multiband wireless application is presented and investigated in this manuscript. Initially, three iterations of DSFA are designed and found that second iteration reveals the more number of frequency bands as compared to the other iterations. For proper impedance matching characteristics, partial ground plane has been introduced in the designing of antenna and low-cost FR4 glass epoxy substrate with thickness of 1.6 mm is used with an overall size of 32 × 36 mm2. Further, the EC parasitic SRR is loaded in the geometry of the proposed antenna and compared with the unloaded antenna and noted that the loaded antenna reports the better results in terms of bandwidth and reflection coefficient. The loaded antenna exhibits the maximum bandwidth of 5.68 GHz (1.67–7.34 GHz) and a maximum gain of 8.63 dB at 2.3 GHz and 9.90 dB at 19.9 GHz. The prototype of the proposed DSFA has been fabricated and tested for the authentication of measured results with the simulated results and found both are in agreement with each other. Proposed DSFA with EC parasitic SRR is best suitable for different wireless applications because of its multiband behaviour.

3D-to-2D phase transformation through highly ordered 1D crystals from transition-metal oxides to dichalcogenides

Although solid-state phase transformations through chemical reaction with the surrounding environment are important in the field of materials science, the atomic-level dynamics at reacting surfaces have been difficult to observe directly. Herein, we found highly ordered arrays of 1D intermediate crystals with a unique atomic configuration during the thermal sulfidation of 3D-structured MoO2 to 2D layer-structured MoS2. These arrays reveal a dimension-breaking reconstruction process (3D → 1D → 2D) as well as a unique electronic structure evolution. Theoretical calculations show that the 1D crystals have a cross-sectional structure of four transition-metal atoms arranged in a diamond shape; these are critical to the atomic layer-by-layer formation of 2D transition-metal dichalcogenides. Furthermore, electronic structure analyses reveal that the 1D intermediate crystals alter the MoO2/MoS2 contact structure from p- to n-type with increases in the number of formed MoS2 layers.