Search

The decrease in dynamic elastic modulus is a primary indicator of quantitative damage in concrete. To quantitatively assess depth-by-depth damage within a concrete structure, cylindrical specimens obtained through coring can be cut into disk specimens to measure the dynamic elastic modulus of concrete at each depth. To minimize external damage during coring, it is essential to extract cylinders with the smallest possible diameter. In addition, for higher resolution in depth-based damage assessment, creating disk specimens with the smallest possible thickness is necessary. However, there is no information available in the literature on experimental limitation of smallest possible diameter and thickness for dynamic elastic modulus of disk-shaped specimens. This study evaluated whether the dynamic modulus measured from various sizes of concrete disk specimens provided sufficient reliability compared to reference values obtained from cylinders. Moreover, the study examined how the presence of coarse aggregate and variation in the water–cement ratio significantly influenced the dynamic modulus measurement. In addition, test results from impulse excitation technique (IET) and impact resonance (IR) were compared to find a more reliable test method for dynamic elastic modulus of disk specimen. The experimental findings revealed that as the thickness-to-radius ratio of the disk specimens decreased, measured data variation increased. Mortar specimens without coarse aggregates showed less variability compared to concrete specimens, and the variation in dynamic modulus measured by IR was lower than that measured by IET. [ABSTRACT FROM AUTHOR]

Background Quality of life (QoL) may be affected due to various reasons such as low back or leg pains with accompanying neurologic problems. Lumbar disk surgery is one of the most common performed surgeries to relieve those symptoms. Various anesthetic techniques can be used safely to perform lumbar disk surgeries. Properties that make an anesthetic technique good are mainly the quick onset and returning of the effects. This large retrospective study with patients who have undergone lumbar disk surgery under spinal anesthesia aims to evaluate the perioperative and postoperative parameters of the spinal anesthesia and review the literature. Methods Cases operated under spinal anesthesia between January 2017 and December 2020 were investigated, and 617 patients who underwent simple lumbar disk surgery were included in the study. Demographic characteristics and American Society of Anesthesiologists (ASA) physical status of the patients were recorded. Visual analog scale (VAS) and QoLscores were obtained before and after the operation. Results There were 282 (45.7%) male and 335 (54.3%) female patients with a mean age of 39.48 ± 16.71 years (range: 18–58 years) at symptom onset. The mean operating time was 46.3 minutes (range: 22–68 minutes). Average blood loss was 85 mL (range: 55–125 mL). All the patients were mobilized 6 to 12 hours after surgery. In our patient group, there were both high- and normal-risk groups in terms of the ASA physical status. During the clinical follow-up, a statistically significant improvement was found for the VAS and QoL scores (p < 0.05). Conclusions In this large retrospective study, our results have confirmed that spinal anesthesia is at least comparable to general anesthesia and even superior to it in some aspects. [ABSTRACT FROM AUTHOR]

The study of nanofluids using a stretchy disc has lately gained importance in fluid mechanics. This work investigates the impacts of the Cattaneo-Christov model, heat radiation, and melting events on TiO2–Al2O3/water and Ag–MoS2/water hybrid nanofluids over a disc. The results show that hybrid nanofluids greatly increase the thermal conductivity and heat transfer capabilities of base fluids. Water-based hybrid nanofluids are used in military applications such as solar thermal energy, heating pumps, heat exchanger devices, ships, air cleaners, the automotive industry, electric chillers, nuclear-powered systems, turbines, and equipment. To explain the flow of hybrid nanofluids, the two-dimensional nonlinear governing equations, which include the continuity, momentum, and heat transfer rate equations, are expressed in a non-dimensional form. The bvp4c solver firing technique in MATLAB is used to solve these non-dimensional equations and investigate the physical effects of various parameters on velocity and temperature profiles. Increasing the magnetic parameter and nanoparticle volume fraction substantially affects the velocity profile in opposing flow. Greater values of the thermal radiation and heat source-sink parameters result in a greater temperature profile. In addition, raising the thermal relaxation and melting parameters improves the temperature profile. The study's findings may be utilized in various sectors, including drainage, chemical engineering, solar panels, solar absorption and filtration, groundwater hydrology, solar cells, and other sheet flow applications. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine, develop mathematical models, and optimize the in-row seed distribution uniformity performance of a vacuum-type seed metering unit in peanut seeding under different operating conditions. The greased belt stand trials based on the Central Composite Design (CCD) were. Quality of feed index, multiple index, miss index, precision, and coefficient of precision were examined as dependent variables, while the peripheral speed of the seed plate, hole diameter of the seed plate, and vacuum pressure were selected as independent variables. Based on the analysis of experimental data from five different levels of each independent variable, performed using the CCD, a meaningful mathematical model was developed in cubic form for the quality of feed index for peanut seeding, and the model was optimized. The ideal conditions were determined from the model as 0.079 ms−1, 6.94 mm, and 7.07 kPa for peripheral speed of the seed plate, hole diameter, and vacuum pressure, respectively. Based on the findings, quality in seeding by selecting the parameters that affect the performance of precision peanut seeding can be enhanced, resulting in valuable information that can be used as a useful guide to farmers, machine manufacturers, and researchers. [ABSTRACT FROM AUTHOR]

Abstract The decrease in dynamic elastic modulus is a primary indicator of quantitative damage in concrete. To quantitatively assess depth-by-depth damage within a concrete structure, cylindrical specimens obtained through coring can be cut into disk specimens to measure the dynamic elastic modulus of concrete at each depth. To minimize external damage during coring, it is essential to extract cylinders with the smallest possible diameter. In addition, for higher resolution in depth-based damage assessment, creating disk specimens with the smallest possible thickness is necessary. However, there is no information available in the literature on experimental limitation of smallest possible diameter and thickness for dynamic elastic modulus of disk-shaped specimens. This study evaluated whether the dynamic modulus measured from various sizes of concrete disk specimens provided sufficient reliability compared to reference values obtained from cylinders. Moreover, the study examined how the presence of coarse aggregate and variation in the water–cement ratio significantly influenced the dynamic modulus measurement. In addition, test results from impulse excitation technique (IET) and impact resonance (IR) were compared to find a more reliable test method for dynamic elastic modulus of disk specimen. The experimental findings revealed that as the thickness-to-radius ratio of the disk specimens decreased, measured data variation increased. Mortar specimens without coarse aggregates showed less variability compared to concrete specimens, and the variation in dynamic modulus measured by IR was lower than that measured by IET.

Abstract Background Cefiderocol is a siderophore-conjugated cephalosporin increasingly used in the management of Achromobacter infections. Testing for cefiderocol susceptibility is challenging with distinct recommendations depending on the pathogens. Objectives We evaluated the performance of commercial tests for testing cefiderocol susceptibility in the Achromobacter genus and reviewed the literature. Methods Diffusion (disks, MIC gradient test strips [MTS], Liofilchem) and broth microdilution (BMD) methods (ComASP™, Liofilchem; UMIC®, Bruker) were compared with the BMD reference method according to the EUCAST guidelines on 143 Achromobacter strains from 14 species with MIC50/90 of ≤ 0.015/0.5 mg/L. A literature search was conducted regardless of method or species. Results None of the methods tested fulfilled an acceptable essential agreement (EA). MTS displayed the lowest EA (30.8%) after UMIC® (49%) and ComASP™ (76.9%). All methods achieved an acceptable bias, with MICs either underestimated using MTS (-1.3%) and ComASP™ (-14.2%) or overestimated with UMIC® (+ 9.1%). Inhibition zone diameters ranged from 6 to 38 mm (IZD50/90=33/30 mm). UMIC® and ComASP™ failed to categorize one or the two cefiderocol-resistant strains of this study as resistant unlike the diffusion-based methods. The literature review highlighted distinct performance of the available methods according to pathogens and testing conditions. Conclusions The use of MTS is discouraged for Achromobacter spp. Disk diffusion can be used to screen for susceptible strains by setting a threshold diameter of 30 mm. UMIC® and ComASP™ should not be used as the sole method but have to be systematically associated with disk diffusion to detect the yet rarely described cefiderocol-resistant Achromobacter sp. strains.

There is a rising incidence of disk battery ingestion in children. This is due to their increased use in electronic devices (including toys) commonly found in the home setting. Children below the age of 6 years are mostly affected with peak incidence in the ages of 1 to 3 years. Although most disk batteries when ingested pass through the gastro intestinal tract harmlessly, they may be lodged in the oesophagus causing significant destructive injury within 4-6 hours of impaction due to their corrosive nature. Impaction of foreign bodies may present with specific symptoms, non specific symptoms or may be asymptomatic. We present an 11 month old child in whom an ingested disc battery had been lodged in the oesophagus for 6 days prior to retrieval by rigid endoscopy. The presence of a clinical history and examination findings supporting a diagnosis of acute tonsillitis was misleading, causing regrettable delays in the diagnosis and management of this child, who subsequently developed a tracheoesophageal fistula. A high index of suspicion by clinicians is needed especially in the non verbal child for early identification and to prevent complications. Increased awareness by parents and other care givers of the hidden dangers of these innocuous -looking batteries in homes and legislation directing the need for child safety locks on disk battery compartments of electronic gadgets and toys will help in reducing the incidence of battery ingestion cases in children.

Background: Cefiderocol is a siderophore-conjugated cephalosporin increasingly used in the management of Achromobacter infections. Testing for cefiderocol susceptibility is challenging with distinct recommendations depending on the pathogens. Objectives: We evaluated the performance of commercial tests for testing cefiderocol susceptibility in the Achromobacter genus and reviewed the literature. Methods: Diffusion (disks, MIC gradient test strips [MTS], Liofilchem) and broth microdilution (BMD) methods (ComASP™, Liofilchem; UMIC®, Bruker) were compared with the BMD reference method according to the EUCAST guidelines on 143 Achromobacter strains from 14 species with MIC50/90 of ≤ 0.015/0.5 mg/L. A literature search was conducted regardless of method or species. Results: None of the methods tested fulfilled an acceptable essential agreement (EA). MTS displayed the lowest EA (30.8%) after UMIC® (49%) and ComASP™ (76.9%). All methods achieved an acceptable bias, with MICs either underestimated using MTS (-1.3%) and ComASP™ (-14.2%) or overestimated with UMIC® (+ 9.1%). Inhibition zone diameters ranged from 6 to 38 mm (IZD50/90=33/30 mm). UMIC® and ComASP™ failed to categorize one or the two cefiderocol-resistant strains of this study as resistant unlike the diffusion-based methods. The literature review highlighted distinct performance of the available methods according to pathogens and testing conditions. Conclusions: The use of MTS is discouraged for Achromobacter spp. Disk diffusion can be used to screen for susceptible strains by setting a threshold diameter of 30 mm. UMIC® and ComASP™ should not be used as the sole method but have to be systematically associated with disk diffusion to detect the yet rarely described cefiderocol-resistant Achromobacter sp. strains. Highlights: Performance of commercial methods are highly diverse and species-dependent. The use of MTS is discouraged due to low essential agreement. UMIC® and ComASP™ failed to detect one or the two cefiderocol-resistant strains. UMIC® or ComASP™ should not be used as the sole method for Achromobacter cefiderocol susceptibility testing. A threshold diameter of 30 mm is proposed for susceptible strain screening. [ABSTRACT FROM AUTHOR]

In this paper, we study the Rosenzweig–MacArthur predator–prey model with predator-taxis and time delay defined on a disk. Theoretically, we studied the equivariant Hopf bifurcation around the positive constant steady-state solution. Standing and rotating waves have been investigated through the theory of isotropic subgroups and Lyapunov–Schmidt reduction. The existence conditions, the formula for the periodic direction and the periodic variation of bifurcation periodic solutions are obtained. Numerically, we select appropriate parameters and conduct numerical simulations to illustrate the theoretical results and reveal quite complicated dynamics on the disk. Different types of rotating and standing waves, as well as more complex spatiotemporal patterns with random initial values, are new dynamic phenomena that do not occur in one-dimensional intervals. [ABSTRACT FROM AUTHOR]

For efficient heating and cooling applications, minimum wall shear stress and maximum heat transfer rate are desired. The current study optimized the local skin friction coefficient and Nusselt number in Al2O3-Cu/water hybrid nanofluid flow over a permeable shrinking rotating disk. First, the governing equations and boundary conditions are solved numerically using the bvp4c solver in MATLAB. Von Kármán's transformations are used to reduce the partial differential equations into solvable non-linear ordinary differential equations. The augmentation of the mass transfer parameter is found to reduce the local skin friction coefficient and Nusselt number. Higher values of these physical quantities of interest are observed in the injection case than in the suction case. Meanwhile, the increase in the magnitude of the shrinking parameter improved and reduced the local skin friction coefficient and Nusselt number, respectively. Then, response surface methodology (RSM) is conducted to understand the interactive impacts of the controlling parameters in optimizing the physical quantities of interest. With a desirability of 66%, the local skin friction coefficient and Nusselt number are optimized at 1.528780016 and 0.888353037 when the shrinking parameter ( λ ) and mass transfer parameter ( S ) are −0.8 and −0.6, respectively. [ABSTRACT FROM AUTHOR]

An hourglass-shaped magnetic field pattern arises naturally from the gravitational collapse of a star-forming gas cloud. Most studies have focused on the prestellar collapse phase, when the structure has a smooth and monotonic radial profile. However, most observations target dense clouds that already contain a central protostar, and possibly a circumstellar disk. We utilize an analytic treatment of the magnetic field along with insights gained from simulations to develop a more realistic magnetic field model for the protostellar phase. Key elements of the model are a strong radial magnetic field in the region of rapid collapse, an off-center peak in the magnetic field strength (a consequence of magnetic field dissipation in the circumstellar disk), and a strong toroidal field that is generated in the region of rapid collapse and outflow generation. A model with a highly pinched and twisted magnetic field pattern in the inner collapse zone facilitates the interpretation of magnetic field patterns observed in protostellar clouds. [ABSTRACT FROM AUTHOR]

The fused deposition modeling (FDM) technique is widely used in different industries due to its low cost and ability to produce complex geometries from polymers. In this technique, some manufacturing parameters are essential because of their effects on the mechanical performance of the final fabricated part. The current study investigated the impact of path strategy and printing speed, two key manufacturing factors, on the mechanical performance of printed disks. Six types of path strategies of rasters corresponding to the loading direction, namely unidirectional-vertical, unidirectional-horizontal, unidirectional-45, cross, cross-45, and concentrate, were used for printing some disks, and compressive tests were done on them. The results showed that these path strategies' average compressive failure loads were 2955, 4957, 2342, 4640, 3971, and 5893 N, respectively. The lower compressive strength of the unidirectional path pattern was due to the weak zones that were located between the printed layers and rasters. Besides, three printing speeds of 40, 60, and 80 mm/s were considered to fabricate the disks with a concentrate path pattern, and compressive experiments were performed. The results showed that the 40 mm/s printing speed conducted a compressive failure load of 4544 N, while 60 and 80 mm/s resulted in 3008 and 2828 N, respectively. Finally, inter-layer strength as a major factor in controlling the compressive strength of the disks was comprehensively discussed. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The rock-breaking force of the disk cutter is affected by many factors. The greater the rock-breaking force applied to the disk cutter, the higher the breakage efficiency and removal in the rock masses, thereby speeding up the excavation speed and improving construction efficiency. The elastic-plasticity of rock materials will greatly affect the disk cutter rock-breaking force, thereby affecting the efficiency and speed of the TBM excavation process. The commercial finite element software LS-DYNA was performed to simulate the rock breakage mechanism by disk cutter, and the influence of three rock behavior models of elastic-plastic, plastic, and elastic models on the rock-breaking force by disk cutter was studied. Finally, the elastic model with the least influencing parameters was selected to study the effects of rock elastic modulus and disk-cutting depth on rock-breaking force. [ABSTRACT FROM AUTHOR]

A spherical convex body R is called reduced if any convex body properly contained in R has thickness smaller than the thickness Δ (R) of R. We show that for every reduced spherical convex polygon V there exists its boundary point such that the disk of radius Δ (V) centered at this point contains V. [ABSTRACT FROM AUTHOR]

The pulse operation is implemented by cooling steam on the flue gas turbine disk to solve online the problem of scaling in the flue gas turbine that affects the safe and long-term operation of the unit. Attempt to adjust the cooling steam flow rate of the flue gas turbine disk and pulse change the disk temperature. By utilizing the difference in expansion coefficient between the catalysts fouling layer and the disk metal, the fouling layer changes relatively slowly and has a small rate of change. The fouling layer is separated, falls off, and is blown away from the disk. By controlling the pulse change process of the disk temperature, the impact of operation on the smooth operation of the rotor component is minimized to the greatest extent. The pulse operation process takes into account both the process stability and the descaling effect. The setting is as follows: slowly increase the cooling steam flow rate from the normal amount of 800 kg/h to 1,500 kg/h at a rate of 50 kg/h per 5 minutes, and then reduce it to the normal amount at the same rate. During the process, the temperature of the disk decreases from 320 °C to 290 °C and then recovers to 320 °C. Within 1 to 2 weeks after the pulse operation, the vibration of the flue gas turbine shaft gradually decreases to a lower level, and there is no significant change in the following 3 months. The goal of improving the dynamic balance of the flue gas turbine rotor online, reducing vibration, and ensuring a 100% synchronous operation rate between the unit and the device has been achieved. [ABSTRACT FROM AUTHOR]

In this paper, we prove that all the eigenvalues of arbitrarily complex matrix are located in one closed disk, which is a refinement of some existing inequalities. [ABSTRACT FROM AUTHOR]

Bladed disks are important components of gas turbine engine. Rotor disk spool drum assemblies of gas turbine engine constitute 20–25% of total engine weight. Increasing thrust-to-weight ratio and engine life is paramount for designers. Blisk reduces significantly weight of rotor, compared against conventional disks for aero engines. This paper brings out specific challenges faced while re-designing bladed disk into blisks including structural integrity aspects under various operating loads. This paper presents a case study on re-design of typical compressor bladed disk into a blisk, without changing the flow path or airfoil configuration, within space constraints. Weight reduction of rotor disk is carried out using shape optimization technique. Blisk configuration is derived from existing bladed disk general arrangement. This paper describes methodology of weight optimization of blisk using 'HyperStudy' tool considering static and dynamic 3D models with ANSYS solver. APDL fatigue life macro is developed for fatigue life prediction, using strain-life approach. In this paper 3D bladed disk, baseline and optimized 3D blisk modal analyses results are used to ensure minimum interferences for engine operating conditions. The developed methodology for optimization can be appreciated by significant weight reduction (30%), while meeting design criteria and increased fatigue life. [ABSTRACT FROM AUTHOR]

The main purpose of this paper is to prove the following result: Let be a -disjoint finite family of disks with the property that every four of them have a common line transversal. Then there exists a line transversal to all members of . Moreover, we prove that the number is sharp. [ABSTRACT FROM AUTHOR]

This review provides a detailed description of the imaging features of cervical spondylotic myelopathy and radiculopathy, with a focus on MRI. Where relevant, we will outline grading systems of vertebral central canal and foraminal stenosis. Whilst post-operative appearances of the cervical spine are outside the scope of this paper, we will touch on imaging features recognised as predictors of clinical outcome and neurological recovery. This paper will serve as a reference for both radiologists and clinicians involved in the care of patients with cervical spondylotic myeloradiculopathy. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine, develop mathematical models, and optimize the in-row seed distribution uniformity performance of a vacuum-type seed metering unit in peanut seeding under different operating conditions. The greased belt stand trials based on the Central Composite Design (CCD) were. Quality of feed index, multiple index, miss index, precision, and coefficient of precision were examined as dependent variables, while the peripheral speed of the seed plate, hole diameter of the seed plate, and vacuum pressure were selected as independent variables. Based on the analysis of experimental data from five different levels of each independent variable, performed using the CCD, a meaningful mathematical model was developed in cubic form for the quality of feed index for peanut seeding, and the model was optimized. The ideal conditions were determined from the model as 0.079 ms−1, 6.94 mm, and 7.07 kPa for peripheral speed of the seed plate, hole diameter, and vacuum pressure, respectively. Based on the findings, quality in seeding by selecting the parameters that affect the performance of precision peanut seeding can be enhanced, resulting in valuable information that can be used as a useful guide to farmers, machine manufacturers, and researchers.

For efficient heating and cooling applications, minimum wall shear stress and maximum heat transfer rate are desired. The current study optimized the local skin friction coefficient and Nusselt number in Al2O3-Cu/water hybrid nanofluid flow over a permeable shrinking rotating disk. First, the governing equations and boundary conditions are solved numerically using the bvp4c solver in MATLAB. Von Kármán’s transformations are used to reduce the partial differential equations into solvable non-linear ordinary differential equations. The augmentation of the mass transfer parameter is found to reduce the local skin friction coefficient and Nusselt number. Higher values of these physical quantities of interest are observed in the injection case than in the suction case. Meanwhile, the increase in the magnitude of the shrinking parameter improved and reduced the local skin friction coefficient and Nusselt number, respectively. Then, response surface methodology (RSM) is conducted to understand the interactive impacts of the controlling parameters in optimizing the physical quantities of interest. With a desirability of 66%, the local skin friction coefficient and Nusselt number are optimized at 1.528780016 and 0.888353037 when the shrinking parameter (λ) and mass transfer parameter (S) are −0.8 and −0.6, respectively.

In this article, we consider the problem of the evolution of the disk subsystem of galaxies, taking into account their halos. The global structure of the disk of galaxies strongly depends on the mass and shape of the halo. To this end, we have studied the evolution of nonradial oscillations of a nonstationary disk surrounded by a passive ellipsoidal halo with a uniform density. A system of equations for the evolution of a self-gravitating disk is obtained, taking into account the halo, in the form of matrix differential equations, and a method for its numerical analysis is developed to study the effect of the halo on disk formation. Numerical calculations were performed for various values of the system parameters, such as the initial perturbation, the circular speed of disk rotation, the ratio of the mass of the halo to the mass of the disk, and the time dependences of the major and minor semiaxes of the disk. The critical values of the system parameters are determined at which the halo stabilizes nonlinear and nonradial oscillations of the disk subsystem of galaxies at an early stage of their evolution.

Abstract This study reveals the impact of heat generation and variable strength of rotation on the unsteady flow of a hybrid nanofluid over a rotatable disk with stretching characteristics and deceleration. A novel mathematical model specifically tailored to elucidate the behavior of a hybrid nanofluid is proposed. By employing similarity variables, the governing model is reformulated into ordinary differential equations (ODEs). The bvp4c function (MATLAB) is employed to efficiently obtain the numerical solutions of these ODEs. To provide a comprehensive study, a stability analysis is also conducted to investigate the properties associated with the non-unique dual solutions generated by the model. Dual solutions are generated, and both are analyzed to be stable. A lower amount of heat generation with greater disk rotation strength is recommended to further improve the heat transfer rate of the model. The bifurcation point is absent within the setup ranges of the parameters in the present study, which suggests a well-maintained laminar flow simulation. The findings of this study offer valuable insights and can assist other researchers in improving their understanding and modeling of similar fluid flow systems, particularly hybrid nanofluid flow systems. [ABSTRACT FROM AUTHOR]

Our goal was to determine if "Nomenclature 2.0," the classification of lumbar disk pathology consensus, should be updated. We conducted a social media and e-mail-based survey on preferences regarding the use of classification on magnetic resonance spine reporting. Members of the European Society of Neuroradiology, European Society of Musculoskeletal Radiology, American Society of Neuroradiology, and American Society of Spine Radiology received a 15-question online survey between February and March 2022. A total of 600 responses were received from 63 countries. The largest number of responses came from Italy and the United States. We found that 71.28% of respondents used Nomenclature 2.0, Classification of Lumbar Disk Pathology. But classification on stenosis is used less often: 53.94% and 60% of respondents do not use any classification of spinal canal stenosis and foraminal stenosis, respectively. When queried about which part of Nomenclature needs improving, most respondents asked for a Structured Reporting Template (SRT), even though 58.85% of respondents do not currently use any template and 54% routinely use a clinical information questionnaire. These results highlight the importance of an updated Nomenclature 3.0 version that integrates the classifications of lumbar disk disease and spinal canal and foraminal stenosis. Further attention should also be directed toward developing a robust endorsed SRT. [ABSTRACT FROM AUTHOR]

Real-time condition monitoring of various types of machinery using sensor technology has gained significant importance in recent years. However, relying on batteries to power these sensors proves to be sub-optimal, as it necessitates regular charging or replacement. To address this, harvesting waste energy from ambient sources emerges as a more efficient alternative. Everyday applications like vehicle wheels, fans, and turbines present ambient sources of waste rotational energy. In this study, we propose a novel rotational energy harvester design that converts rotational energy into linear energy. This linear energy impacts a piezoelectric disk, generating an electric potential. Through simulations, the expected electric potential at varying frequencies was evaluated. Subsequently, experimental tests were conducted by connecting the harvester to a rectifier for AC-to-DC signal conversion and an oscilloscope for voltage measurement. A DC motor replicated the rotational motion at the frequencies from the simulation, and the power output was measured. Using the power transfer theorem, simulation and experimental power outputs were calculated, resulting in values of 188, 513, and 1293 μW and 88.89, 336, and 923 μW, respectively. These results reveal that the designed harvester is competitive with those of existing rotational energy harvester designs, demonstrating the promising potential of this novel harvester. [ABSTRACT FROM AUTHOR]

Annular fissures are common findings on MR studies of the lumbar spine but have not been specifically examined in the thoracic spine. We sought to review the prevalence and stability of MRI imaging features of thoracic annular fissures and the association of thoracic AFs with intervertebral degenerative disk changes. We surveyed 10 years of MRI studies in which patients had one or more repeated examinations of the thoracic spine. For every annular fissure, we recorded its imaging features on all pulse sequences and the evolution of those imaging findings across all time periods. We reviewed 210 patients and discovered that 66 (31.4%) had at least one thoracic annular fissure. The presence of annular fissures was positively correlated with older age and male gender. The initial annular fissure was always hyperintense on T2WI and annular fissures remained hyperintense on T2WI over time in all cases but showed less hyperintensity in 23.9% (n = 39/163) and more hyperintensity in 4.9% (n = 8/163). The rate of concomitant disk bulges was 85.8% (n = 140/163). Of the 71 annular fissures in which gadolinium-enhanced studies were performed, 20 (28.1%) showed enhancement and 14/20 (70%) annular fissures showed persistent enhancement over time (mean follow-up = 39.6 ± 44.1 months). Thoracic annular fissures rarely resolve, remain hyperintense on T2WI, and, if they enhance, that enhancement generally persists. • The thoracic annular fissures were always hyperintense on T2WI over time in all thoracic intervertebral disks. • The size of the thoracic annular fissures remained stable in 73.6% disks overtime. • The rate of concomitant disk bulges was 85.8% among all intervertebral disks with annular fissures. • The patients with concomitant disk bulges and thoracic annular fissures were older than those without disk bulges. [ABSTRACT FROM AUTHOR]

We prove that a disjoint family of seven or more unit circular disks in the plane has a support line provided every its subfamily of three disks has a support line. This result corrects our previous assertion that number six is sufficient here. [ABSTRACT FROM AUTHOR]

Background: 'Temporomandibular joint disorders (TMDs)' denote an umbrella term that includes arthritic, musculoskeletal and neuromuscular conditions involving the temporomandibular joint, the masticatory muscles, and the associated tissues. Occlusal devices are one of the common treatment modalities utilized in the conservative management of TMDs. The indications for the available 'oral splints' or 'oral orthotic occlusal devices' remain ambiguous. Methods: A joint international consortium was formulated involving the subject experts at TMJ Foundation, to resolve the current ambiguity regarding the use of oral orthotic occlusal appliance therapy for the temporomandibular joint disorders based on the current scientific and clinical evidence. Results: The recommendations and the conclusion of the clinical experts of the joint international consort has been summarized for understanding the indications of the various available oral orthotic occlusal appliances and to aid in the future research on oral occlusal orthotics. Conclusion: The use of the oral orthotic occlusal appliances should be based on the current available scientific evidence, rather than the archaic protocols. [ABSTRACT FROM AUTHOR]

Urartians ruled over the regions mainly around three lakes of Van, Sevan and Urmia from about 9th to 7th centuries BC and several metal artefacts are discovered less in situ in the Urartian sites. Among them are bronze discs which are slightly convex or convex in the middle. There is a newly found convex in the middle disc of Argišti I from Qala Dağı, Kiqal Varzaqan, Iran which is similar to the disc in Tabriz Museum also from Varzaqan in the inscription and to the disc in Van Museum in the form. There also is a hieroglyphic sign over the disc which was common on the other discs. The epigraphy of the cuneiform inscription on the mentioned disc was used widely in the Urartian kingdom since Minua’s reign until Sarduri II’s. It is the aim of this paper to introduce this newly discovered artifact and to review the function and forms of the discs which could be used as horse harness or buttons of the armors or clothing. Additionally, the authors try to compare the discs of Argišti I in the epigraphy and form. The authors recognized that the epigraphy of Minua’s reign to Sarduri II’s were also used on the discs inscribed with the name of King Išpuini, Minua’s father, and Inušpua, Minua’s son who never ruled. Therefore, it is possible that the newly found disc is not inscribed during Argišti I’s reign but his son Sarduri’s but as most of the discovered discs bear the name of Argišti it is possible that there was a mass production of the discs during his reign and was brought to Eastern Azerbaijan Province after his reign.

An hourglass-shaped magnetic field pattern arises naturally from the gravitational collapse of a star-forming gas cloud. Most studies have focused on the prestellar collapse phase, when the structure has a smooth and monotonic radial profile. However, most observations target dense clouds that already contain a central protostar, and possibly a circumstellar disk. We utilize an analytic treatment of the magnetic field along with insights gained from simulations to develop a more realistic magnetic field model for the protostellar phase. Key elements of the model are a strong radial magnetic field in the region of rapid collapse, an off-center peak in the magnetic field strength (a consequence of magnetic field dissipation in the circumstellar disk), and a strong toroidal field that is generated in the region of rapid collapse and outflow generation. A model with a highly pinched and twisted magnetic field pattern in the inner collapse zone facilitates the interpretation of magnetic field patterns observed in protostellar clouds.

The utilization of Maxwell fluid with nanoparticle suspension exhibits promising prospects in enhancing the efficacy of energy conversion and storage mechanisms. They have the potential to be utilized in sophisticated cooling systems for power generation facilities, thereby augmenting the overall energy efficacy. Keeping this in mind, the current research examines the Maxwell nanofluid flow over a rotating disk with the impact of a heat source/sink. The present study centers on the examination of flow characteristics in the existence of a uniform magnetic field. The conversion of governing equations into ordinary differential equations is achieved using appropriate similarity variables. To derive the Nusselt number (Nu) and skin friction (SF) model related to the flow and temperature parameters, the suggested back-propagation artificial neural networking (ANN) technique is used. The Runge-Kutta-Fehlberg fourth-fifth order (RKF-45) method is used to solve the reduced equations and produce the necessary data to create the Nu and SF model. Both the Nu and SF models require 1000 data for training the network, respectively. Graphs are utilized to communicate numerical outcomes. The results concluded that the upsurge in magnetic parameter drops the velocity profile but advances the heat transport. Rise in the thermal conductivity parameter, increases the heat transport.

We present a numerical approach for computing attractive-repulsive power law equilibrium measures in arbitrary dimension. We prove new recurrence relationships for radial Jacobi polynomials on d-dimensional ball domains, providing a substantial generalization of the work started in Gutleb et al. (Math Comput 9:2247–2281, 2022) for the one-dimensional case based on recurrence relationships of Riesz potentials on arbitrary dimensional balls. Among the attractive features of the numerical method are good efficiency due to recursively generated banded and approximately banded Riesz potential operators and computational complexity independent of the dimension d, in stark constrast to the widely used particle swarm simulation approaches for these problems which scale catastrophically with the dimension. We present several numerical experiments to showcase the accuracy and applicability of the method and discuss how our method compares with alternative numerical approaches and conjectured analytical solutions which exist for certain special cases. Finally, we discuss how our method can be used to explore the analytically poorly understood gap formation boundary to spherical shell support. [ABSTRACT FROM AUTHOR]

A uniform motion of a disk in horizontal direction along its axis of symmetry in a stratified viscous fluid at rest is studied. The disk generates three-dimensional internal gravity waves occupying the entire volume between the disk and the location of its start. The waves are observed using two-color, beta-plus visualization of the vortex flow structure calculated within the framework of the system of Navier–Stokes equations in the Boussinesq approximation. The results of the study complete considerably the earlier-published mechanism of the formation of half-waves above the axis of symmetry of the disk, where emphasis was placed on the periodic process of generation of deformed vortex rings above the location of the disk start. Their generation is due to gravitation and shear instabilities, when the left semi-ring is transformed into a half-wave of depressions or crests, while the right one vanishes with time. In this paper it is established that the left parts of the right odd semi-rings are transformed into the axial parts of the crest half-waves. [ABSTRACT FROM AUTHOR]

The primary objective of the present numerical analysis is to investigate the effect of a mixed convection flow around a disk containing hybrid nanofluid as graphene oxide (GO)‐molybdenum disulfide (MoS2) nanoparticles and water (H2O). This study examines the impacts of surface suction/injection, slip effect, magnetohydrodynamic effect, the shape of nanoparticles, and heat transfer characteristics, on a disk is analyzed. This research applies to disk‐shaped structures in aeronautical engineering, geophysics, and nuclear engineering, such as core catchers in nuclear power plant steam turbines, waxy crude oils or food products in centrifugal pumps, turbo‐machinery, and other industrial processes. Nonlinear partial differential equations (PDEs) with subjected surface restrictions represent this study's governing equations. It's a PDE. The Von Karman transformation can simplify PDEs into non‐dimensional ordinary differential equations, which can be solved using the MATLAB bvp5c function. The research findings indicate that the presence of hybrid nanoparticles results in a significant increase in the heat transfer rate compared to that of the nanoliquid. Increasing the strength of the magnetic field slows down the flow of a hybrid nanofluid. The gradient value pronounces impacts with increasing slip factor. The heat transfer rate increases significantly with the increase of sphericity of the nanoparticles. [ABSTRACT FROM AUTHOR]

We study some disks contained in the filled-in Julia sets associated with the complex polynomials of the form f(z) = zn + c for some values c ∈[-2, 1/4] and n ≥ 2. [ABSTRACT FROM AUTHOR]

This article deals with the study of thermal stress and angular speed in a rotating disk made of polymer (say natural rubber/polypropylene) under the effect of thermal, thickness and mechanical load and fitted with rigid shaft. Seth's transition theory and generalized strain measure are used for finding the governing equation. Mathematical modeling is based on stress –strain relation and equilibrium equation. The effects of different pertinent parameters (i.e., load, temperature and thickness) are considered for disk made of natural rubber/polypropylene material. The behaviour of stress distribution, angular speed, mechanical load and temperature distribution are investigated. From the obtained results, it is noticed that, natural rubber disk requires higher angular speed to yield at the inner surface in comparison to polypropylene disk. The theoretical results are validated by comparing them with those obtained by Thakur after performing some significant calculation examples. [ABSTRACT FROM AUTHOR]

Subject and Purpose. Considered in the paper is diffraction of a plane wave by a structure involving a half-plane and two disks. The disks and the half-plane, lying within parallel planes, are assumed to be infinitely thin and perfectly conducting. The problem is to be analyzed for two cases, namely for that of both disks located on the same side with respect to the half-plane, and for the other where they are placed on opposite sides against the half-plane. The purpose of the paper is to develop a suitable operator method for performing the analysis of the structure described. Methods and Methodology. The solution to the problem has been sought for within the operator method suggested. The electric field components tangential to the half-plane and the disks are expressed, with the aid of Fourier integrals, via some unknown functions having the sense of amplitudes. The unknown amplitudes shall obey the operator equations formulated in terms of wave scattering operators for individual disks and the sole half-plane. Results. When subjected to certain transformations, the operator equations allow obtaining integral equations relative amplitudes of the spherical waves involved. The integral equations permit investigating scattered wave fields for the cases where the disks stay in the shadow region behind the half-plane or in the penumbra, or else in the region which is illuminated by the incident wave. As has been shown, in the case of plane wave scattering at the edge of the half-plane the resulting cylindrical waves possess non-zero amplitudes even with the disks placed totally in the shadow region, hence not illuminated by the incident plane wave. Conclusions. Making use of an operator method, an original solution has been obtained for the problem of plane wave diffraction by a structure consisting of a perfectly conducting, infinitely thin half-plane and two disks. The operator equations of the problem have been shown to be reducible to integral equations, further solvable numerically with the use of discretization based on quadrature rules. The behavior of far and near fields relative to the disks has been studied for a variety of values of the disk radii and their positions relative to the half-plane.

The scattering by the perfectly electric conducting (PEC) half-plane and PEC zero thickness disk placed on parallel planes is considered. The fields are represented in the spectral domain, i.e. in the domain of Fourier transform. The operator equations with respect to the Fourier amplitudes of the scattered field are obtained. The kernel functions of these equations contain poles. After regularization procedure, which is connected with the elimination of the poles, operator equations are converted to the system of singular integral equations. The convergence of the solution is based on the corresponding theorems. The scattered field consists of the plane wave, reflected by the infinite part of the half-plane, cylindrical waves, which appear as a result of scattering by the edge of the half-plane, and spherical waves, which appear as a result of scattering by the disk and multiple re-scattering by the disk-half-plane. The total near-field distribution and far-field patterns of cylindrical waves are presented. [ABSTRACT FROM AUTHOR]

The thermal performance of slotted bicycle discs are compared to a solid bicycle disc. Four commercial 160 mm diameter bicycle brake discs were modelled with computational fluid dynamics simulations, including all the geometrical design features, such as holes, slots/cutouts, corner radii, and the brake track to hub radial spokes. Three of the discs had holes or slots in the brake track, and the other had a solid brake track. Turbulent simulations were performed in STAR-CCM + , a commercial computational fluid dynamics code, using transient time stepping to capture the rotation, forward speed, and the dynamic nature of heat transfer from the discs. Nusselt number vs. crossflow Reynolds number heat transfer correlations are provided and compared to existing rotating disc in crossflow studies. Additionally, a bicycle was instrumented for downhill front braking tests on a constant slope hill subjected to both low and high external wind driven convection. Brake temperatures, pressures, altitudes, speeds and infrared thermographic images are presented and discussed. The three slotted brake discs were shown to have higher convection coefficients from computational fluid dynamics simulations, and correspondingly lower temperatures during downhill tests than the solid brake disc. Overall, the three slotted discs had better thermal performance than the solid disc. [ABSTRACT FROM AUTHOR]

Data centers are located centralized to do computation and accessing huge amount of data by the network devices which are interconnected to form the network path. Servers are stacked, data storage is placed in them. Data server backup and server redundancies are the recovery mechanisms implemented. Data centers compute, store, distribute the data by processing them and the data center controls all the interconnected network equipment in the distributed network. In current, RAID system is implemented to avoid the service disruptions due to disk failures, the availability of system and services are achieved with this expensive model. But still the availability is lost, and service disruptions happen due to disk failures, the machine learnings models to be used to predict the disk failures well in advance. Data center has increased usage of system with increased data storage, the failure in disc makes the system failed and down time increases. Analysis on the methods of problems in disk and methods of disk availability and predict the disk failure is the main goal. Various machine learning models are identified and discussed along with the SMART parameters for measuring the failure of the disk. Improved method of Ensembling of trees, random forest and boosting techniques are also discussed. [ABSTRACT FROM AUTHOR]