Bead Pattern Research Articles

Topography optimization of an enclosure panel for low-frequency noise and vibration reduction using the equivalent radiated power approach

An enclosure panel is widely used in industrial applications. The panel under a dynamic loading excites the surrounding air medium and noise is radiated into the acoustic space. The radiated sound can be suppressed by having changes in the structure. The noise reduction performance can be further improved by a design optimization. In this study, a topography optimization is conducted to design an enclosure panel. Topography optimization results in a bead pattern, which helps maintain the thickness at a constant level throughout the structure. The final optimized structure can be manufactured using a stamping process. Compared with other optimization methods, topography optimization requires minimal manufacturing effort and cost, with no additional increase in mass. Moreover, this type of optimization is effective for noise reduction problems because no holes are created in the structure. In this study, the objective function selected to minimize the low-frequency noise is the equivalent radiated power. The topography optimization of the enclosure panel has been conducted using the commercial software Altair OptiStruct, with loads and constraints considered. In order to verify the optimization result, in-situ experiment was performed with panels produced by the stamping process.

Thin Film PZT-Based PMUT Arrays for Deterministic Particle Manipulation

Lead zirconate titanate (PZT)-based piezoelectric micromachined ultrasonic transducers (PMUTs) for particle manipulation applications were designed, fabricated, characterized, and tested. The PMUTs had a diaphragm diameter of 60 [Formula: see text], a resonant frequency of ~8 MHz, and an operational bandwidth (BW) of 62.5%. Acoustic pressure output in water was 9.5 kPa at 7.5 mm distance from a PMUT element excited with a unipolar waveform at 5 Vpp . The element consisted of 20 diaphragms connected electrically in parallel. Particle trapping of 4 [Formula: see text] silica beads was shown to be possible with 5 Vpp unipolar excitation. Trapping of multiple beads by a single element and deterministic control of particles via acoustophoresis without the assistance of microfluidic flow were demonstrated. It was found that the particles move toward diaphragm areas of highest pressure, in agreement with literature and simulations. Unique bead patterns were generated at different driving frequencies and were formed at frequencies up to 60 MHz, much higher than the operational BW. Levitation planes were generated above the 30 MHz driving frequency.

Fracture and fragmentation patterns within a single cemented glass bead under impact

Dynamic fracture and fragmentation within cemented granular materials play a significant role in controlling industrial comminution and blasting processes. In this study, impact experiments using a Hopkinson bar facility demonstrate that the damage pattern in a system of a single brittle glass bead covered by epoxy cement is highly dependent on the absorbed energy. Under small to moderate impacts the damage preferentially occurs in the cement material, while under stronger impacts the damage is prone to occur in the glass bead. Quantitative analysis using X-ray micro-computed tomography supports the understanding that friction is the most prominent energy dissipation mechanism, particularly during severe fragmentation processes. Using innovative techniques based on Fourier transform, the locality of damage within the cemented bead is then quantitatively analysed, as well as their preferential crack orientation. The resulting analysis shows that damage is most likely to occur along the central loading axis area of the cemented bead and forms cracks propagating through the bead along the impact direction, a pattern that is strikingly different from the failure pattern of non-cemented glass beads. Meanwhile, the central plane normal to the impact direction has the typical coplanar cracks, accompanied by oblique cracks (roughly 45∘ or 135∘ inclined to the loading direction) near the centre of the glass bead.

SCL: a lattice-based approach to infer 3D chromosome structures from single-cell Hi-C data.

MotivationIn contrast to population-based Hi-C data, single-cell Hi-C data are zero-inflated and do not indicate the frequency of proximate DNA segments. There are a limited number of computational tools that can model the 3D structures of chromosomes based on single-cell Hi-C data.ResultsWe developed single-cell lattice (SCL), a computational method to reconstruct 3D structures of chromosomes based on single-cell Hi-C data. We designed a loss function and a 2 D Gaussian function specifically for the characteristics of single-cell Hi-C data. A chromosome is represented as beads-on-a-string and stored in a 3 D cubic lattice. Metropolis–Hastings simulation and simulated annealing are used to simulate the structure and minimize the loss function. We evaluated the SCL-inferred 3 D structures (at both 500 and 50 kb resolutions) using multiple criteria and compared them with the ones generated by another modeling software program. The results indicate that the 3 D structures generated by SCL closely fit single-cell Hi-C data. We also found similar patterns of trans-chromosomal contact beads, Lamin-B1 enriched topologically associating domains (TADs), and H3K4me3 enriched TADs by mapping data from previous studies onto the SCL-inferred 3 D structures.Availability and implementationThe C++ source code of SCL is freely available at http://dna.cs.miami.edu/SCL/.Supplementary information Supplementary data are available at Bioinformatics online.

Nanocomposite of Polyacrylonitrile/Modified Polyethersulfone and Carbon Nano-onion: Effect of Dispersion on Physical Features, Interface and Fracture Behavior

In this effort, novel blend of polyacrylonitrile and modified polyethersulfone (PAN/mod-PES) were designed. Two series of nanocomposite were prepared using resin infiltration technique with 0.5-5wt.% carbon nano-onion (CNO) and functional carbon nano-onion (F-CNO) i.e. PAN/mod-PES/CNO 0.5-5 and PAN/mod-PES/F-CNO 0.5-5. Microstructure studies revealed pattern of small beads homogeneously dispersed in form of arrays. Inclusion of 5wt.% nanofiller decreased molecular weight of PAN/mod-PES/CNO 5 and PAN/mod-PES/F-CNO 5 to 110 × 103 and 71 × 103g/mol, respectively, relative to neat blend (160 × 103g/mol). Shear stress of PAN/mod-PES/F-CNO 0.5-5 was found higher than neat blend. Thermal stability of functional nanocomposite was considerably enhanced with nanofiller loading compared with non-functional CNO and attained V-0 rating. Maximum thermal stability was achieved with 5wt.% F-CNO content i.e. T0, T10, and Tmax of 503, 539, and 615 °C, respectively. Higher functional nanofiller loading also enhanced tensile, flexural, and impact strength of nanocomposite up to 63, 189, and 9.7 J/m. Fracture toughness of PAN/mod-PES/F-CNO also significantly improved with bonding time and annealing temperature owing to intermolecular reactions, molecular diffusion occurring at interface, and bonding mechanism. At 200 °C, energy of adhesion attained high value of 930 J/m2 (1h). Besides, PAN/mod-PES with 5 wt.% F-CNO own higher KIC of 0.87MPa m0.5 among nanocomposite.

REVERSIBLE CEREBRAL VASOCONSTRICTION SYNDROME IN THE BACKDROP OF CEREBRAL VENOUS THROMBOSIS: A POST-PARTUM CATASTROPHE

Reversible cerebral vasoconstriction syndrome (RCVS) is an under-recognized condition characterized by the association of acute severe headaches, often of the thunderclap type, with or without additional neurological symptoms, and multifocal constriction of cerebral arteries, that resolve spontaneously within 1–3 months. Here, we report a rare case of post-partum stroke, where cerebral venous thrombosis was followed in quick succession by RCVS. A 24-year-old lady in her immediate post-partum period developed headache, seizure, and papilledema. After a subsequent episode of a severe headache, she had right hemiparesis and dysarthria. Computed tomography and magnetic resonance venography confirmed the presence of thrombosis. Afterward, she had another episode of a severe headache with altered sensorium. MR imaging of the brain revealed widespread infarct in bilateral medial frontal areas, and MR angiography was suggestive of segmental constriction of cerebral arteries bilaterally. The subsequent clinical course was uneventful with slow recovery. Repeat brain imaging, after 4 weeks, revealed near-total disappearance of diffusion restriction and subsidence of the beading pattern in the cerebral vasculature. This rare case depicts the co-occurrence of venous and arterial angiopathies in the setting of a post-partum headache with the stroke that led to a challenging clinical scenario.

OR8 A novel reactivity pattern with labscreen™ class I single antigen beads and its prevalence among SLE patients

Aim Previously, a distinct class II Luminex-single antigen bead (SAB) pattern was described among patients with systemic lupus erythematous (SLE) and attributed to antibodies targeting denatured antigens. In this study, we identify and describe a novel class I reactivity pattern shared among SLE patients. Methods Routine review of serum samples from transplant patients revealed a recurring pattern of reactivity on class I single antigen bead assays (One Lambda, Inc, lot 10). The pattern included the following beads: HLA-A∗33:03, -A∗36:01, -A∗80:01, -B∗54:01, -B∗53:01, -C∗06:02, -C∗07:02, -C∗18:02, -C∗14:02, -C∗03:03, -C∗03:04, and -C∗15:02. Further investigation was performed to determine the prevalence of this pattern and the specific characteristics of patients in which it occurred. Towards this end, all class I results performed in 2017 on renal transplant candidates/recipients were reviewed retrospectively for the presence of the above pattern. Patient diagnosis and demographic data was obtained from patient laboratory and hospital records. Results In total 5,992 samples from 3,027 patients were reviewed. We observed 105 (1.8%) samples from 58 patients displaying the class I pattern. Twenty-nine percent (n = 17) of these patients had no history of sensitization (e.g. blood transfusion, pregnancy, transplant) and only 29% of samples had distinct antibodies as identified by FlowPRA testing. Of the positive samples, 83% had reactivity against self-antigen involving 1 or more of the alleles in question, with HLA-C∗07:02 being the most common target (45%). Notably, 62% of these patients had a diagnosis of SLE. Conclusions To our knowledge, this is the first description of a distinct class I Luminex-SAB pattern with a prevalence in patients with SLE. This pattern was found in patients with no sensitization history, negative FlowPRA, and/or antibody to self-antigen(s). Epitope analysis failed to reveal a common determinant(s) to explain this pattern of reactivity. Given these findings, this pattern likely represents antibody targeting denatured antigen/unique peptide, molecular mimicry, autoimmunity, or a combination of some/all these factors.

Simulation of spatial diffusion of platinum from carboplatin-impregnated calcium sulfate hemihydrate beads by use of an agarose gelatin tissue phantom.

OBJECTIVE To characterize spatial release of platinum from carboplatin-impregnated calcium sulfate hemihydrate (CI-CSH) beads by use of an agarose tissue phantom. SAMPLE 3-mm-diameter beads (n = 60) containing 4.6 mg of carboplatin (2.4 mg of platinum)/bead. PROCEDURES 18 L of 1% agarose was prepared and poured into 36 containers (10 × 10 × 10 cm), each of which was filled half full (0.5 L/container). After the agarose solidified, 1, 3, 6, or 10 CI-CSH beads were placed on the agar in defined patterns. An additional 36 blocks of agar (0.5 L/block) were placed atop the beads, positioning the beads in the center of 1 L of agar. The experiment was replicated 3 times for each bead pattern for 24, 48, and 72 hours. At these times, representative agarose blocks were sectioned in the x-, y-, and z-planes and labeled in accordance with their positions in shells radiating 1, 2, 3, 4, and 5 cm from the center of the blocks. Agarose from each shell was homogenized, and a sample was submitted for platinum analysis by use of inductively coupled plasma-mass spectroscopy. RESULTS Platinum diffused from CI-CSH beads at predicted anticancer cytotoxic concentrations for 2 to 5 cm. CONCLUSIONS AND CLINICAL RELEVANCE Results provided information regarding the spatial distribution of platinum expected to occur in vivo. Agarose may be used as a diffusion model, mimicking the characteristics of subcutaneous tissues. Measured platinum concentrations might be used to guide patterns for implantation of CI-CSH beads in animals with susceptible neoplasms.

VALUES WHICH ARE REPRESENTED BY THE PATTERNS ON PRA-GUAM SILVER BEADS OF KHMER PEOPLE IN KHAWAO SINARIN VILLAGE SURIN PROVINCE, THAILAND

This aims of this study are 1) to study the physical patterns on Pra-guam Silver beads 2) To study the basic beliefs represented by the patterns on Pra-guam Silver beads 3) to Study the doctrines which are represented by the patterns on Pra-guam Silver beads 4) To Study the Values which are represented by the patterns on Pra-guam Silver beads. The qualitative research methodology was used in this study by using in-depth-interviews, Participation and Observation. The key participants of the study were Monks, Experts, Academics and Artisans in Kha-Wao Sinarin Village Surin Province, Thailand. The results were that the patterns consist of ancient patterns transferred down from ancestor. the patterns represented were 1) the lotus flower 2) Ma-Yom seed 3) Phigool flower 4) Hae and 5) Jarl 1) the Lotus flower represents the base of belief in Holy Symbolism 2) Ma-Yom Seed stands for the base belief in Popularity 3) Phigool flower is representive of the Symbolism of Ritualism 4) Hae represents the base belief in Ghost and the Devil 5) Jarl reflects the base of belief in the Power of black Magic. The doctrines which are represented on the patterns of Pra-guam Silver beads were 1) the Lotus flower is a Cultural Symbol to represent respectfulness and humility.2) the Ma-Yom seed is a Cultural Symbol that represents thinking carefully and With Circumspection 3) Phigool flower stands for the equality of humanity and justice. 4) Hae is a Cultural Symbol to reflect the belief in thinking carefullyand solving problems in an appropriate manner 5) Jarl is a Cultural symbol that represents the uncertainly of life and trying to do good things. The Values of the patterns on Pra-Guam Silver beads, Cultural Symbol represented the extrinsic values in regard to the spiritual anchor on faith and life safety and Intrinsic Values represented physical beauty on ethnical identity art or design.

Meroitic beadwork: an overview based on finds from Saï in ancient Nubia

The paper provides a preliminary overview of beads and pendants found on Saï Island at two Meroitic cemeteries, 8-B-5.A and 8-B-52.B. In the Meroitic period, strings of beads and pendants were an easily discerned motif in royal and private iconography, as well as in the arts and crafts, pottery included. The Saï bead and pendant assemblage is characterized by a variety of materials, techniques, and shapes that contribute significantly to a comparative study of Meroitic beadwork bead collections. Alongside objects already identified at other sites, richly imbued with visible Egyptian and Greek influences, the Saï assemblage contributes some new bead types. Moreover, the originally strung objects and their fragments confirm known bead patterns used over a long time between the 1st and 4th centuries AD, the date of the Saï necropolises. Finally, a comparison with other sites enables the tracing of some regional differences in Meroitic beadwork.

Node-based free-form optimization method for vibration problems of shell structures

We have previously proposed a numerical node-based parameter-free shape optimization method for designing the optimal free-form surface of shell structures. In this paper, this method is extended to deal with two vibration problems including a vibration eigenvalue maximization problem and a frequency response minimization problem. To avoid the repeated eigenvalue problem when a specified vibration eigenvalue is maximized, we provide two optional approaches, i.e., tracking the specified natural mode or increasing all the repeated eigenvalues. Each vibration problem is formulated as a distributed-parameter shape optimization problem, and the derived shape gradient function is applied to the H1 gradient method for the shells proposed by the authors, where the shape gradient function is used as a distributed force function to vary the surface. With this method, the optimal and smooth free-form shape including a natural bead pattern can be obtained. Several calculated examples are presented to demonstrate the effectiveness of the proposed method for the free-form design of shell structures involving vibration problems.

On the occurrence of ‘bead lightning’ phenomena in long laboratory sparks

The formation of bead lightning, where the lightning channel appears to break up into luminous fragments, is still an object of speculation. Here we report similar observations in laboratory discharges. Analysis of time resolved photographs shows that the discharge channel exhibits a ‘bead pattern’ in the decaying stage of the discharge and the occurrence of loops in the channel sections where the bead pattern is observed. This result presents the first evidence that the rapid cooling of non-uniform channel sections could lead to the formation of beads. It is suggested that periodically occurring non-uniform channel sections could explain the bead pattern of lightning discharges.

Tears of wine: new insights on an old phenomenon.

Anyone who has enjoyed a glass of wine has undoubtedly noticed the regular pattern of liquid beads that fall along the inside of the glass, or ‘tears of wine.’ The phenomenon is the result of a flow against gravity along the liquid film on the glass, which is induced by an interfacial tension gradient. It is generally accepted that the interfacial tension gradient is due to a composition gradient resulting from the evaporation of ethanol. We re-examine the tears of wine phenomenon and investigate the importance of thermal effects, which previously have been ignored. Using a novel experiment and simple model we find that evaporative cooling contributes significantly to the flow responsible for wine tears, and that this phenomenon occurs primarily because of the thermodynamic behavior of ethanol-water mixtures. Also, the regular pattern of tear formation is identified as a well-known hydrodynamic instability.

A REVIEW OF GLASS COMPOSITIONS AROUND THE SOUTH CHINA SEA REGION (THE LATE 1ST MILLENNIUM BC TO THE 1ST MILLENNIUM AD): PLACING IRON AGE GLASS BEADS FROM TAIWAN IN CONTEXT

With more published chemical analyses of glass beads in Southeast Asia and southern China in the last decade, it is becoming possible to discuss the regional and temporal patterns of prehistoric glass beads in these areas. This article focuses the 1st millennium AD, reviewing the chemical composition of glass in Taiwan, Southeast Asia and southern China, in an attempt to understand the potential relationships between the three regions.

Springback-Free Sheet Metal Structural Part Design by Topography Optimization

Topographgy optimization is a special kind of size optimization and it has been widely used to enhance the stiffness of sheet metal formed component by adding beads to the geometry. In this paper we present a methodology on how this concept can be employed in order to reduce formed part geometry deviation due to springback. An automotive part from Numisheet benchmark 2008 was used in this study. Several bead patterns were first generated by topography optimization subject to load constraints. Then the effects of these bead patterns location and size were studied by numerical forming and springback simulation. Our results show that the bead patterns have a significant effect on the springback. Finally, a methodology has been developed so that springback-free design can be incorporated in the early stage of part design.

Cellphone Camera Imaging of a Periodically Patterned Chip as a Potential Method for Point-of-Care Diagnostics

In this study, we demonstrate that a disposable chip periodically patterned with suitable ligands, an ordinary cellphone camera, and a simple pattern recognition software, can potentially be used for quantitative diagnostics. A key factor in this demonstration is the design of a calibration grid around the chip that, through a contrast transfer process, enables reliable analysis of the images collected under variable ambient lighting conditions. After exposure to a dispersion of amine terminated silica beads used as analyte mimicking pathogens, an epoxy-terminated glass substrate microcontact printed with octadecyltrichlorosilane (250 μm periodicity) developed a characteristic pattern of beads which could be easily imaged with a cellphone camera of 3.2 MP pixels. A simple pattern recognition algorithm using fast Fourier transform produced a quantitative estimate of the analyte concentration present in the test solution. In this method importantly, neither the chip fabrication process nor the fill-factor of the periodic pattern need be perfect to arrive at a conclusive diagnosis. The method suggests a viable platform that may potentially find use in fault-tolerant and robust point-of-care diagnostic applications.

Experimental Investigation and Performance Enhancement of Inserts in Composite Parts

New joining technologies are needed due to the increased use of carbon fibre reinforced plastics (CFRP) in the automotive industry. Traditional joining technologies cannot fulfill the requirements, especially for multimaterial assemblies of CFRP and metal. A suitable technology for the integration of mounting points in CFRP parts is the embedding of inserts. In this paper, two approaches to increase the tensile and bending strength of inserts are evaluated experimentally. Bead patterns are added in the metal sheet of the inserts to increase stiffness. Furthermore, surface treatments are used to enhance the co-cured bonding strength between insert and CFRP.

Geometrical Frustration in Amorphous and Partially Crystallized Packings of Spheres

We study the persistence of a geometrically frustrated local order inside partially crystallized packings of equal-sized spheres. Measurements by x-ray tomography reveal previously unseen grain scale rearrangements occurring inside large three-dimensional packings as they crystallize. Three successive structural transitions are detected by a statistical description of the local volume fluctuations. These compaction regimes are related to the disappearance of densely packed tetrahedral patterns of beads. Amorphous packings of monodisperse spheres are saturated with these tetrahedral clusters at Bernal's limiting density (φ≈64%). But, no periodic lattice can be built upon these patterns; they are geometrically frustrated and are thus condemned to vanish while the crystallization occurs. Remarkably, crystallization-induced grain rearrangements can be interpreted in terms of the evolution of key topological features of these aggregates.

Synthetic Fourier transform light scattering

We present synthetic Fourier transform light scattering, a method for measuring extended angle-resolved light scattering (ARLS) from individual microscopic samples. By measuring the light fields scattered from the sample plane and numerically synthesizing them in Fourier space, the angle range of the ARLS patterns is extended up to twice the numerical aperture of the imaging system with unprecedented sensitivity and precision. Extended ARLS patterns of individual microscopic polystyrene beads, healthy human red blood cells (RBCs), and Plasmodium falciparum-parasitized RBCs are presented.

Attomolar protein detection using a magnetic bead surface coverage assay

We demonstrate a microfluidic method for ultra-sensitive protein detection in serum. First, 'large' (2.8 μm) antibody-functionalized magnetic beads specifically capture antigen from a serum matrix under active microfluidic mixing. Subsequently, the large beads loaded with the antigens are gently exposed to a surface pattern of fixed 'small' (1.0 μm) antibody-coated magnetic beads. During the exposure, attractive magnetic bead dipole-dipole interactions improve the contact between the two bead types and help the antigen-antibody immunocomplex formation, while non-specific large bead adsorption is limited by exploiting viscous drag forces in the microfluidic channel on the small-bead pattern. This efficient antigen-antibody recognition and binding mechanism mimics a biological process of selective recognition of tissue molecules, like is the case when leukocytes roll and slow down on blood vessel walls by selectin-mediated adhesion. After exposure of the large beads to the pattern of small beads, the antigen concentration is detected by simply counting the number of surface pattern-bound large magnetic beads. The new technique allows detection of proteins down to the sub-zeptomole range. In particular, we demonstrate detection of only 200 molecules of Tumor Necrosis Factor-α (TNF-α) in a serum sample volume of 5 μL, corresponding to a concentration of 60 attomolar or 1 fg mL(-1).