bluuebunny/crossref_metadata_2025 huggingface dataset:
Virtual care in the health care system: A concept analysis
Authors: Babaei Nasib , Zamanzadeh Vahid , Valizadeh Leila , Lotfi Mojgan , Kousha Ahmad , Samad‐Soltani Taha , Avazeh Marziyeh
Published: November 2023

Background

Health care providers need a better understanding of virtual care to recognise and use it for service delivery.

Aim

To provide a more comprehensive definition of the concept of virtual care.

Method

This study was conducted based on Walker and Avant's concept analysis method. A comprehensive review of the published texts in English from 2012 to 2022 was performed using the PubMed, Web of Science, Scopus, ProQuest, Science Direct, Ovid, CINAHL and Google Scholar databases.

Results

The main aspects and attributes of virtual care, including the use of any information and communication technology in various formats such as platforms, telephone calls, messages, email consultation, remote monitoring, secure and two‐way digital communication between health care providers and patients, the possibility of providing remote care synchronously or asynchronously, more interaction between patients and caregivers, the possibility of transferring information between patients and health care providers and within the teams themselves, symptom management, sending diagnostic results in the form of video visits, and providing follow‐up care, are attributes that distinguish virtual care from telehealth, telemedicine and other methods of providing remote healthcare services.

Conclusion

Considering the positive and negative consequences of implementing virtual care, the findings of this study developed a basis for an operational definition of the concept so that providers can understand the meaning of virtual care and consider it when providing virtual care to patients. The findings of this study can be used in many international and national contexts in the health care system and in future studies on interventions to increase the use of virtual care.
Ambiguity in Language and Logic
Authors: Wurm Christian
Published: November 2023

This article gives an explanation of how recent results on ambiguity logics are relevant to the linguistic and philosophical theory of ambiguity. To this aim, some fundamental definitions and results are explained. We formulate and provide evidence for three main hypotheses: Firstly, ambiguity is not a vague notion. Secondly, in (explicit) reasoning with ambiguity, we always have to consider the parameter trust. Thirdly, ambiguous propositions exist, but they cannot have the same rights and properties as unambiguous propositions; rather they should be considered “second class”.
Computed tomographic, magnetic resonance imaging, and ultrasonographic characteristics of retrobulbar meningiomas in 15 dogs
Authors: Sidhu Amit , DeJesus Antonia A
Published: November 2023

Meningioma is the most common tumor of the cranium in dogs and an important differential diagnosis for a potentially treatable disease that can be found in the periorbital tissues. The objective of this retrospective, case series study was to describe the CT, MRI, and US characteristics of confirmed retrobulbar meningiomas in a group of dogs. Medical records from multiple institutions were searched for canine patients with CT, MRI, and/or US imaging of a cytologically or histologically confirmed retrobulbar meningioma. Fifteen dogs met the inclusion criteria. Retrobulbar meningiomas typically appeared as a relatively well‐defined conical to ovoid mass within the retrobulbar space, most often along the optic nerve and expanding the extraocular muscle cone. On CT, masses were predominantly soft tissue attenuating and variably heterogeneously contrast enhancing. While MRI features were variable, moderate to marked contrast enhancement was seen in all cases. Many of the tumors had evidence of partial mineralization, best appreciated on CT in nine patients, but also suspected based on susceptibility artifacts in three MRI cases, one of which was confirmed on CT. Regional osteolysis was a rare finding, noted in three cases, but was often accompanied by cranial cavity extension (2/3). Cranial cavity extension was also seen in the absence of regional osteolysis, identified in a total of six patients. On US, masses were echogenic and compressed the globe. The findings were consistent with previous gross and histologic descriptions and supported prioritizing retrobulbar meningioma as a differential diagnosis for dogs with the described imaging characteristics.
The Relative Importance of Destructive Analyses for Radiological Characterization With Geostatistics
Authors: Desnoyers Yvon
Published: November 2023

Geostatistics provides innovative tools for the radiological characterization of nuclear facilities under decommissioning as well as contaminated sites for remediation. The relevance of this approach relies on the presence of a spatial continuity for radiological contamination. In this case, geostatistics provides reliable activity estimates, uncertainty quantification and risk analysis, which are essential decision-making tools for decommissioning and dismantling projects of nuclear installations.

The experimental variogram γ(h) is calculated by averaging, within classes of distance h, the variability contribution of each couple of data; this contribution is usually quantified by the half-squared difference of the measured values. In this paper, a parallel is drawn with an alternative formula of the statistical variance to be able to break down the different variance contribution (sampling duplicates, measurement replicates, spatial variability). The application on one chemical case and one radiological case demonstrates that, the relative uncertainty on the laboratory results (analyses on destructive samples) can be seen as negligible in comparison to the sampling uncertainty on the one hand and the spatial variability on the other hand.

In addition, classification of volumes according to a threshold seems to be quite robust in comparison to the relative accuracy of the lab results. The artificial introduction of a systematic bias (± 50% for instance) leads to a corresponding limited impact on contaminated volumes (only ± 10% or ±20%).
Comparison Between Different Source Reconstruction Methods of Atmospheric Leakages
Authors: Xu Yuhan , Fang Sheng
Published: November 2023

When a severe nuclear accident occurs, the diffusion and transportation of airborne radioactive materials can cause harmful effects on the public. An accurate source release rate assessment is necessary to evaluate the consequence of the accident. Provided the leakage source location is known, the source inversion method can inversely estimate the release rate by coupling environmental measurements and the atmospheric dispersion model. Since the Fukushima nuclear accident, source inversion has significantly progressed over the past decade. However, the recent accidental radionuclide leakages are characterized by unknown source locations, causing difficulties in source inversion. Consequently, source reconstruction that simultaneously localizes the atmospheric leakage source and retrieves the release rate has become a highly prevailing and challenging topic.

In this study, we introduce and compare three source reconstruction schemes: the cost function method, the source-receptor sensitivity (SRS) statistical method, and the Bayes method. The benchmark SRS data are generated by the backward mode of the FLEXPART model. All methods are validated by the European Tracer Experiment-the first release (ETEX-I). The results indicate the respective advantages and disadvantages in source reconstruction, among which the Bayes method achieves the highest accuracy whereas the cost function method achieves the lowest computational cost. In addition, we compare the source reconstruction performance between the two Bayes methods with the assumption of constant release and time-varying release, respectively. The source release rates in all schemes (if needed) are estimated using the traditional Tikhonov regularization method. The results demonstrate that the Bayes method with constant release may contribute to the best source reconstruction performance. In summary, the above source reconstruction methods are suitable for different emergency response scenarios or stages, thus having the potential to be integrated into the nuclear emergency and response system.
Wind Tunnel Validation Study of Joint Estimation Source Term Inversion Method
Authors: Hu Hao , Dong Xinwen , Li Xinpeng , Xu Yuhan , Zhuang Shuhan , Fang Sheng
Published: November 2023

Radioactive emissions caused by severe accidents pose a great threat to the environment and creatures along the spread. The source inversion technique is designed to retrieve the corresponding release rate based on environmental monitoring data and has been widely integrated into the nuclear accident consequence assessment. The Model error and its propagation in the inversion cause the estimate unrealistic and confuse the real releases. Several self-correcting source inversion methods have been proposed to handle it, for instance, the joint estimation method that simultaneously retrieves the estimate and corrects the model bias by introducing a correction coefficient matrix. In this study, the joint estimation method has been investigated against a wind tunnel experiment with the incoming airflow from the southeast direction (SSE). Three nuclear power plants were located in the scenario, surrounded by mountains and sea. The Risø Mesoscale Lagrangian PUFF model (RIMPUFF) was used for atmospheric diffusion predictions and the transport matrix construction. The fine wind tunnel experimental data was used as the observations to drive the standard (Tikhonov) inversion method and the joint estimation method. The results show that the release rate estimated by the Tikhonov method was four times higher than the ground truth on the representative SSE direction. In comparison, the self-correcting joint estimation method reduces the error to only 4%.
Survivability and Reliability Testing and Modeling of Printed Hybrid Electronic (PHE) Assemblies Subject to Extreme Acceleration Levels
Authors: Richards Hayden , Abusalma Hisham , Dasgupta Abhijit , Yu Jian , Bujanda Andres , Tsang Harvey
Published: November 2023

Drop testing performance of Printed Hybrid Electronic (PHE) assemblies is reported in this paper. These studies assessed PHE assembly mechanical and electronic survivability and durability in a high-shock acceleration environment using accelerated drop towers equipped with dual-mass shock amplifiers (DMSAs). Testing was completed at accelerations from 10,000 G up to 100,000 G with pulse durations of ∼0.05–0.1 ms and impact velocities of 6.5–20.5 m/s.

The test samples were hemispherical domes fabricated using: (a) additive manufacturing with several different ABS compounds, and (b) injection molding with various EXL9330 and EXL1414 polycarbonates. Different combinations of embedded electronic components ranging from passive components to integrated circuit (IC) packages were subsequently embedded into or surface-mounted onto the exterior face of the dome and interconnected with printed silver traces. Dome modifications were completed using 5-axis CNC machining, silver traces were printed using nScrypt and other extrusion 3D printers, and other IC packages were mounted and connected manually.

Specimens were installed on the drop tower by direct threading into custom aluminum fixtures and instrumented with strain gauges and in-situ resistance measurement cabling. Impacts were characterized with multiple accelerometers mounted to the test fixture and high-speed video controlled by digital acquisition systems at sampling rates up to 1 MHz.

This study considered degradation mechanisms for the substrate material, the electronic component assembly, and the printed silver interconnects. Catastrophic failures of compliant additively manufactured ABS domes at relatively low acceleration levels (10,000–30,000 G) motivated the use of molded polycarbonates, which withstood hundreds of drops at over 100,000 G. Printed electrical trace performance was assessed through 4-point resistance measurements and both pretest and post-test optical microscopy. Trace degradation from as-printed condition to open-circuit failure took as few as 1–2 drops at 100,000 G to hundreds at 10,000–40,000 G. Observed failure modes for traces included 1) failure at locations previously determined during pre-testing microscopy to be ‘at-risk’ sites due to printing issues, 2) delamination of the trace from the substrate material, and 3) cracking across the trace due to dynamic flexural response of the substrate. Prior to failure, resistance measurements for traces progressively increased with number of drops, at rates proportional to acceleration magnitude.
Enhancing Manual Visual Inspection Process by Using OpenCV AI and Anomalib for Defect Detection in Automotive Assembly and Manufacturing Process
Authors: Christie Stewart , Prakash Anna , Ashton Elaina , Tanner Veronica
Published: November 2023

Manual visual inspection process is the most used method for performing visual inspection in the manufacturing of semiconductors electronics. It is a critical quality management procedure that all leading automotive manufacturers continue to perform for defect detection. However, manual inspections can be a slow process and increases the chances for error. Striving for lower error rates requires investment in skilled, experienced, and well-trained inspectors. Adding automation and AI (Artificial Intelligence) capabilities to the manual visual inspection process can help reduce human visual perception errors, reduce defects, and improve process efficiency. In this literature review, we attempt to gain an understanding of existing research on anomaly detection using open-source tools for detecting very small visual defects on thermal Integrated Heat Spreaders (IHS) lids, document challenges related to real world dataset, key learnings, and explore future opportunities in this growing field.
Evolution of Thermal Interface Material-to-Copper Interfacial Fracture Toughness Subjected to Monotonic and Fatigue Loading After Thermal Cycling
Authors: Lall Pradeep , Kasturi Madhu
Published: November 2023

Automotive electronics increasingly use high-performance semiconductors to enable a number of advanced driver assistance systems. Thermal management in chip-based electronic systems is quickly becoming one of the most significant impediments to enhanced performance and integration density. The ongoing downsizing and integration of semiconductor devices have increased by heat generated per unit volume of the chip. Thermal interface material (TIM) facilitates heat dissipation from chip to package and from package to heat sink. Exposure to the wide temperature ranges typical in automotive conditions may result in the early propagation of fractures at the TIM-to-Copper contact, leading to high thermal resistance and device thermal runaway. In this paper, bimaterial samples have been created by dispensing TIM materials onto the copper surface and curing them based on the specified conditions. A total of three different TIM materials are used in this study. Two types of samples are prepared, namely with and without pre-crack. The samples are tested in four-point bend monotonic and fatigue loading conditions. The pre-cracked samples are used for fatigue four-point bend loading, and the no-pre-crack samples are used for monotonic four-point bend loading. Before testing, to calculate the bi-material samples’ KIC and KIIC fracture toughness values, they are subjected to automotive-grade thermal cycling from −40°C to +125°C for up to 1000 cycles. Interfacial crack initiation, propagation, and failure mechanisms are investigated. The interfaces’ strain-energy release rate and fracture toughness are assessed.
A Numerical Study on the Influence of Mixed Convection Heat Transfer in Single-Phase Immersion Cooling
Authors: Saini Satyam , Gupta Gautam , Bansode Pratik , Shahi Pardeep , Simon Vibin Shalom , Modi Himanshu , Agonafer Dereje , Shah Jimil
Published: November 2023

Data centers are critical to the functioning of modern society as they host digital infrastructure. However, data centers can consume significant amounts of energy, and a substantial amount of this energy goes to cooling systems. Efficient thermal management of information technology equipment is therefore essential and allows the user to obtain peak performance from a system and enables higher equipment reliability. Thermal management of data center electronics is becoming more challenging due to rising power densities at the chip level. Cooling technologies like single-phase immersion cooling allow overcoming many such challenges owing to their higher thermal mass, lower fluid pumping powers, and potential component reliability enhancements. It is known that immersion cooling deployments require extremely low coolant flow rates, and, in many cases, natural convection can also be used to sufficiently dissipate the heat from the hot server components. It, therefore, becomes difficult to ascertain whether the rate of heat transfer is being dominated by forced or natural convection. This may lead to ambiguity in choosing an optimal heat sink solution and a suitable system mechanical design due to unknown flow regimes, further leading to sub-optimal system performance. Mixed convection can be used to enhance heat transfer in immersion cooling systems. The present investigation quantifies the contribution of mixed convection using numerical methods in an immersion-cooled server.

An open compute server with dual CPU sockets is modeled on Ansys Icepak with varying power loads of 115W, 160W and 200W. The chosen dielectric fluid for this single-phase immersion-cooled setup is EC-100. Steady-state Computational Fluid Dynamics (CFD) simulations are conducted for forced, natural, and mixed convection heat transfer in a thermally shadowed server configuration at varying inlet flow rates. A baseline heat sink and an optimized heat sink with an increased fin thickness and reduced fin count are utilized for performance comparison. The effect of varying Reynolds number and Richardson number on the heat transfer rate from the heat sink is discussed to assess the flow regime, stability of the flow around the submerged components which depends on the geometry, orientation, fluid properties, flow rate and direction of the flow. The dimensionless numbers’ influence on heat transfer rate from a conventional air-cooled heat sink in immersion versus an immersion-optimized heat sink is also compared. The impact of server orientation on heat transfer behavior for the immersion optimized heat sink is also studied on heat transfer behavior for the immersion optimized heat sink.
Experimental and CFD Analysis of a Rack Manifold for High Power Density Liquid-Cooled Rack
Authors: Shahi Pardeep , Heydari Ali , Bansode Pratik , Siddarth Ashwin , Chowdhury Uschas , Miyamura Harold , Modi Himanshu , Agonafer Dereje , Tradat Mohammad , Rodriguez Jeremy
Published: November 2023

Direct Liquid Cooling (DLC) has emerged as a promising technology for thermal management of high-performance computing servers, enabling efficient heat dissipation and reliable operation. Thermal performance is governed by several factors, including the coolant physical properties and flow parameters such as coolant inlet temperature and flow rate. The design and development of the coolant distribution manifold to the Information Technology Equipment (ITE) can significantly impact the overall performance of the computing system. This paper aims to investigate the hydraulic characterization and design validation of a rack-level coolant distribution manifold or rack manifold. To achieve this goal, a custom-built high power-density liquid-cooled ITE rack was assembled, and various cooling loops were plugged into the rack manifold to validate its thermal performance. The rack manifold is responsible for distributing the coolant to each of these cooling loops, which is pumped by a CDU (Coolant Distribution Unit). In this study, pressure drop characteristics of the rack manifold were obtained for flow rates that effectively dissipate the heat loads from the ITE. The pressure drop is a critical parameter in the design of the coolant distribution manifold since it influences the flow rate and ultimately the thermal performance of the system. By measuring the pressure drop at various flow rates, the researchers can accurately determine the optimum flow rate for efficient heat dissipation. Furthermore, 1D flow network and CFD models of the rack-level coolant loop, including the rack manifold, were developed, and validated against experimental test data. The validated models provide a useful tool for the design of facility-level modeling of a liquid-cooled data center. The CFD models enable the researchers to simulate the fluid flow and heat transfer within the cooling system accurately. These models can help to design the coolant distribution manifold at facility level. The results of this study demonstrate the importance of the design and development of the coolant distribution manifold in the thermal performance of a liquid-cooled data center. The study also highlights the usefulness of 1D flow network and CFD models for designing and validating liquid-cooled data center cooling systems. In conclusion, the hydraulic characterization and design validation of a rack-level coolant distribution manifold is critical in achieving efficient thermal management of high-performance computing servers. This study presents a comprehensive approach for hydraulic characterization of the coolant distribution manifold, which can significantly impact the overall thermal performance and reliability of the system. The validated models also provide a useful tool for the design of facility-level modeling of a liquid-cooled data center.
In-Flight Structural Test of a Hoverbike Using Fiber Optic Sensors
Authors: Hwang Yong-Ha , Jang Kwangwoo , Ahn Hyungjoo , Bang Hyochoong , Han Jae-Hung
Published: November 2023

A hoverbike is a vehicle that can fly and hover. Demand for using hoverbikes in various missions, including transport, surveillance, reconnaissance, and infiltration is increasing. While various attempts have been made to develop hoverbikes, there is still a lack of experimental verification on whether the frame structure of a hoverbike can provide sufficient structural strength to withstand extreme loads that may occur during flight without causing damage. Therefore, in this paper, we aim to experimentally investigate the structural characteristics of the hoverbike frame.

KAIST is developing a hoverbike that can load up to 100 kg. As part of the development process, structural tests were conducted on the hoverbike. Fiber Bragg Grating (FBG) sensors were utilized for the structural testing. The FBG sensor is capable of multiplexing, in which several sensors can be placed on one optical fiber and is not affected by electromagnetic interference (EMI).

Structural strength tests were conducted on the carbon pipes that were used for the manufacturing of hoverbike frames. A down-scaled hoverbike was manufactured. When thrust was generated in the prop connected to the main motor, the dynamic characteristics of the frame was measured. FBG sensor was attached to the frame, and frequency analysis was performed by FFT on the frame strain data measured when thrust was applied. A flight test was performed assuming a rapid maneuvering situation. The maximum bending load generated during rapid maneuvering was calculated using frame strain data. The hoverbike frame was modeled with finite elements, and the internal load analysis was performed by assuming the flight load as a static load. Analysis were compared with flight test, and the validity of the finite element model for internal load analysis was confirmed.
High Load NiTi Shape Memory Alloy Actuators: A Study of Cyclic Behavior
Authors: Thüsing Kai , Hofer Andreas , Pagel Kenny , Weck Christian , Drossel Welf-Guntram
Published: November 2023

This paper advances the knowledge of the cyclic thermomechanical behavior and fatigue of high load SMA-Actuators. Due to their small volume and weight, these actuators provide an attractive alternative to conventional actuators. Especially in production plants and machines, where the requirements for installation space and weight are becoming increasingly crucial for a successful manufacturing process, they find a wide field of application. Quite in contrast to small force applications, more massive geometries and new integration concepts of the shape-memory-components (SMC) are substantial. However, well developed semi-finished products are not yet available. Furthermore, this changes mechanical and functional cycle fatigue, an issue well known from wire based small force SMA-Actuators. Comprehending how these changes significantly alter the SMA behavior will eventually enable novel designing and optimizing. Therefore, the cyclic behavior of the SMC is investigated, using a high load SMA-Actuator, that has been designed for integration in machines tools. The SMCs, cycled in the SMA-Actuator have been manufactured with different methods. Here, a classical manufacturing process is compared to an additive process (PBF-LB/M). The additive processed SMCs show microcracks and pores. Nevertheless, the cyclic properties exceed those of the classical processed specimen in all measured properties. Especially the tiny hysteresis, low shortening of the SMC can be highlighted.
Effect of Hysteresis on a Piezoelectric Inverted Beam Energy Harvester
Authors: Zarepoor Masoud , Bilgen Onur
Published: November 2023

Piezoelectric materials have been used in various types of structures to harvest ambient vibration energy by converting mechanical deformation to electrical charge. The harvested power can be used to charge batteries and/or operate low-power electronics such as wireless sensors. So-called linear piezoelectric devices can harvest vibrational energy efficiently only around the resonant frequency of the device. Ambient vibrations are typically multi-tone excitations with broadband frequency content. As a result, nonlinear piezoelectric harvesters are developed to harvest energy across a wide frequency band. For example, bistable piezoelectric material-based vibration energy harvesters are nonlinear devices with two equilibria, capable of producing large-amplitude motion between the two equilibria where mechanical energy that can be converted to electrical power. An inverted beam with a tip mass can be designed to be bistable and harvest vibrational energy at low frequencies. The tip mass can be selected to place the inverted beam near buckling to cause large geometrically nonlinear deformations at low excitation frequencies. The mathematical modeling dynamical behavior of an inverted beam with a tip mass has been previously investigated. This paper explores the effects of piezoelectric material nonlinearity and hysteresis on the harvested power of an inverted beam vibration energy harvester. This paper utilizes the Bouc-Wen model to describe the nonlinearity and hysteretic behavior of the piezoelectric material. The governing electromechanical equation of motion for an inverted beam energy harvester is derived which includes piezoelectric hysteresis effect as a function of strain. Numerical simulations are presented to show how the piezoelectric material hysteresis changes the harvested electrical power for different excitation amplitudes and frequencies. This paper improves existing nonlinear electromechanical models to produce more accurate results by modeling piezoelectric material hysteresis.
On Phase Coupling of a Vortex-Induced Swing Sensor
Authors: Gong Ying , Peng Qianyi , Li Zhongjie
Published: November 2023

In recent years, the detection of climate and hydrology has become more and more important, and the related research of vortex-induced vibration has also been paid attention. Based on a vortex-induced swing structure that can realize flow direction sensing and energy harvesting, we study the phase coupling problems caused by structural size. In this paper, according to the research on the trajectory of the vortex-induced fluid-structure coupling motion, it is shown that a solid (e.g. cylinder) has the tendency of torsion under laminar impact. While the swing amplitude of the cylinder with a single bluff is low and unable to meet application requirements. Based on fluid-solid boundary layer theory, C shaped elastomer structure is designed to enhance torsional swing. The size of the cylinder and the C-shaped elastomer affects the frequency and phase of vortex-induced swing, and then influences the whole swing amplitude. We established a mathematical model for the phase study. In the experiment, by changing the ratio of the cylinder diameter to the width of the C-shaped elastomer, the swing amplitude characteristic under different conditions is obtained. Results show that when the sum of phase angle superposition is 2kπ + π, the phase coupling is suppressed. The width of C shaped elastomer is 25mm as the cylinder diameter is 18 when the suppression happens.
Determination of Material Parameters and FEM Simulation for the Development of a Design System for Shape Memory Springs
Authors: Hiekel Alexander , Hoffmann Fabian , Krieg Romina , Theiß Ralf , Pagel Kenny , Pelshenke Christian , Horn Simon , Mehrbakhsh Mehrdad , Drossel Welf-Guntram , Dültgen Peter
Published: November 2023

Including characteristic alloy parameters in the design process of shape memory springs is crucial to enhance the performance of the resulting actuator. In contrast to conventional spring steel, shape memory alloys (SMA) show a non-linear stress-strain curve based on a thermal- or stress-induced phase transformation. Substitute models obtained from linear approximations do not adequately represent these material properties. Consequently, the designed actuators are liable to oversizing without fully exploiting the potential strokes and forces. This paper shows an alternate system design method based on cause-effect relationships between the material parameters, the spring geometry, and the resulting actuator behaviour. To identify the relationships, FEM models of various SMA spring geometries, such as helical, shaft and wave springs, were implemented in the ANSYS Mechanical simulation software. Moreover, the springs were manufactured to validate the models using standardized test methods such as tensile-compression tests and DSC (Differential Scanning Calorimetry) measurements. These validated models form the basis to determine the cause effect-relationships via the Design of Experiment (DoE) method. Finally, discrete mathematical descriptions of the relationships are derived and implemented into a shape memory spring layout tool. The derived method achieves a substantially higher accuracy compared to linear substitute models. In addition, it is worth highlighting that the usage of the layout tool does not require special knowledge in thermo-mechanical simulation. Hence, it will be of particular interest for small and medium companies to access the technology more easily.
Econo-Finger: 3D Printed Soft Orthotic Finger With Embedded Strain Gauge and Actuated by Coiled Shape Memory Alloy Muscles
Authors: Miles Drew , Tadesse Yonas
Published: November 2023

Ischemic stroke is a deadly and debilitating medical event that leaves many people with motor disfunction. Post-stroke loss of hand functionality can be restored through powered hand orthosis. Artificial muscles like coiled shape memory alloy (SMA) can provide the necessary tension and pulling force needed to assist with flexion of the digits. Coiled SMA muscles have been implemented in several orthotic devices. One of the greatest obstacles in powered orthotic design is affordability. Leveraging inexpensive manufacturing processes like 3D printing can greatly minimize production and consumer cost and help customization. This would greatly bridge the price gap that exists between passive orthoses and smart feedback-controlled orthoses.

This work proposes an electrically powered single finger soft orthosis with embedded strain gauge made through a single step 3D printing approach. We utilized inexpensive coiled nickel titanium SMA muscles to assist in flexion of the index finger. Using an embedded strain gauge made from conductive thermoplastic polyurethane (CTPU), we can accurately monitor the flexion angle of the index finger. This precise data can be paired with electromyography (EMG) control to produce feedback-controlled movement. The expected fabrication cost of this orthotic finger is below $750, making it much cheaper than other smart powered orthoses currently available. We will show how the device responds to cyclic use under different input parameters. Using these responses, we will develop strategies to leverage the performance of the device for a variety of activities of daily life.
Antibacterial Properties of Snakeskin Inspired PDMS Surfaces Layered With Poly-DL-lactic Acid Nanosheet
Authors: Ibrahim Mohd Danial , Ananthan Alyssa Asong , Abang Mahmod Dayang Salyani , Awang Husaini Awang Ahmad Sallehin , Sing Ngieng Ngui , Nakano Shunsuke , Sunami Yuta , Barroy Pierre
Published: November 2023

The increment of sterilization resistant bacteria minimizes the effectiveness of disinfectants which leads researchers into studying other means in minimizing bacterial contamination on surfaces. Hence, this study plans to investigate surfaces with the ability to discourage bacterial adhesion and reduces the need for frequent sterilization. This study tested the feasibility of applying snakeskin inspired microstructures onto a polydimethylsiloxane (PDMS) surface to reduce bacterial adhesion and increase its antibacterial properties. In theory, the microstructure of snakeskin is smaller or about the same size as a bacterium making it unfeasible for bacterial adhesion. The embeddedelastomeric stamping method was used for the biomimicry of snakeskin onto PDMS surfaces. The replicated snakeskin and controlled (no microstructure) PDMS samples were layered with Poly-DL-lactic acid (PDLLA) nanosheet of different thickness. Then, the morphology of the surfaces was observed using a scanning electron microscope. The surface of the samples was tested with Staphylococcus aureus and Bacillus with compliance of the ISO 22196 standard to evaluate the antimicrobial activity. Our results revealed, surfaces with snakeskin microstructures displayed a 16% reduction in bacterial adhesion compared to flat PDMS. Whereas the presence of nanosheet does not significantly affect the adhesion of bacteria on the replicated snakeskin. These findings suggest that surfaces with the presence of snakeskin microstructures possess antibacterial property.
Annealed Pyrolytic Graphitic Carbon Electrodes for Piezoelectric Acoustic Nanoweb
Authors: Chytanya Chinnam Krishna , Sepehr Moeini Seyed , Tuti Simonetta , Lanzara Giulia
Published: November 2023

The primary challenge in realizing an ultimate lightweight and flexible acoustic sensing device is the electrode material. To obtain the best device performance expensive gold electrodes have been used in the literature due to the relatively higher electrical conductivity. In this paper we implement an annealed pyrolytic graphitic carbon on carbon fibers to form a low-cost highly performing porous electrode for acoustic applications. The electrode is prepared by using a 400-micron thick PMMA membrane electrospun on a unidirectional carbon fiber textile. The electrode is then used to form an acoustic sensor via a hybrid 3D printing-electrospinning-pyrolysis approach which allowed to deliver an overall flexible acoustic device. Preliminary results show a low noise level functional material with reasonably high electromechanical output to a wide range of acoustic frequencies. The higher sensitivity of the material with respect to the devices formed with continuous electrodes, is to be attributed to the porosity of the electrode material which enhances the vibrating air particles to interact with the interacting membrane directly and homogenously.
Investigation of the Thermal Heat Exchange Between NiTi-Wire Bundles and Airflow for Different Wire Arrangements
Authors: Welsch Felix , Kirsch Susanne-Marie , Louia Franziska , Seelecke Stefan , Motzki Paul
Published: November 2023

Nickel-Titanium (NiTi)-based shape memory alloys (SMAs) enable new sustainable and environmentally friendly solid-state heating and cooling technologies. Elastocaloric (EC) heat pump systems exploit superelastic SMAs as a non-volatile, inflammable, and non-global-warming refrigerant, in contrast to the well-established vapor compression technology. The high specific latent heat released or absorbed during mechanical loading or unloading of the SMA material leads to a high temperature change in the material. As a result of the small required work input to induce the phase transformation, a high coefficient of performance (COP) can be achieved by this technology. The potential of these alloys can be exploited through an adequate thermodynamic cycle, efficient mechanical system design, and choice of suited EC materials.

A fully functional continuous operating EC heat pump system based on SMA was developed and realized recently. To assist the design process of an optimized device with given performance and efficiency requirements, the air-cooling behavior of single wires and simple bundle arrangement has been analyzed, and intensive parameter studies on different airflow rates have been performed.

For optimizing the heat transfer using bundles, the influence of different angles of attack between the wire arrangement and the airflow is investigated, and the temperature development in the bundle, as well as the effects on the thermal performance, are presented in this work.
Thermomechanical Processing of NiTiCu Shape Memory Alloy From Button to Wire
Authors: Gantz Faith , Al Jabri Nehal , Worrell Dominique , Young Marcus L. , Palisoc Art
Published: November 2023

Shape memory alloys (SMA) are a lightweight and compact option for actuators because of their high energy density capacity and allowing the system weight to be reduced by a fraction of conventional actuators. An SMA processed into wire with a narrow hysteresis and great thermomechanical stability can ease integration into novel actuation designs. These designs can improve the thermomechanical response and reduce the energy usage, weight, and mechanical complexity of the system. Compositionally substituting Ni for Cu in the NiTi SMA system creates an SMA with these characteristics in comparison to binary NiTi SMAs. In this study, a set of NiTiCu SMA compositions were thermomechanically-processed using conventional methods such as rolling and drawing to produce plates, rods, and 0.50 mm diameter wire. Every processing step was characterized to monitor the evolution of microstructure and thermomechanical properties by using various microscopy, spectroscopy, and diffraction techniques. The NiTiCu wires were shape-set using a custom-made device to form small springs with dimensions specified to an actuating device within the reorientation mechanism of a CubeSat. Springs were made from NiTiCu wires and from commercially available NiTi wires, then thermomechanically cycled 50 times to train and compare the thermoelastic properties and actuation response.
Acoustic Meta-Structure Transmission Loss Characterization via an Impedance Tube and the Transfer Matrix Approach
Authors: Beals Matthew D. , Chavan Shantanu H. , Malladi Vijaya V. N. Sriram
Published: November 2023

This paper proposes a new meta-structure bandgap depth measurement method that considers energy absorption rather than discrete structural response. By applying measurement techniques previously reserved for acoustic property characterization, this novel method aims to characterize acoustic meta-structures by their transmission loss (TL). Transmission loss is the ratio of incident energy to transmitted energy from a structure. One extensively defined testing method for determining acoustic transmission loss involves using an impedance tube or a tube outfitted with transducers flush to its inside wall on either side of a sample holder, along with a source and termination on either end of the tube. Using the transfer matrix approach and transfer functions computed from the impedance tube transducers, the pressure and particle velocity at one point in space and time can be related to that of another point in space and time. In the end, a transfer matrix can be determined, which contains information about how much energy is absorbed, reflected, and transmitted by a structure over an entire range of frequencies. By outfitting an impedance tube to accept acoustic meta-structure samples, this same method can determine the transmission loss versus frequency exhibited by such a structure. This information can be used to directly observe and measure the band gap depth of an acoustic meta-structure.
Dynamic Mode Decomposition Approach for Estimating the Shape of a Cable
Authors: Chavan Yash Manik , Malladi Vijaya V. N. Sriram , Bae Jung Yun , Park Myoungkuk , Krishnan Manu
Published: November 2023

This study investigates the dynamic behavior of a flexible cable with heterogeneous stiffness using a data-driven approach. The study aims to develop accurate models that describe intricate structures with rigid or flexible components. To achieve this, reflective markers were attached to the cable at equal spacing and the motion was manually excited and captured using an 8 camera setup and OptiTrack’s Motive software.

Cable displacement data at marker locations were used as initial conditions for various Dynamic Mode Decomposition (DMD) models. The performance of the data-driven cable model is compared against the performance of the DMD modeling approach, fitting the dynamics of single- and multidegree-of-freedom systems with added white noise. In this work, the authors have considered using time delays and Wavelets-based DMD.

The study found that the wavelet-based DMD (WDMD) model was the most accurate method for reconstructing the response of the cable in the test cases. Researchers suggest that this data-driven approach can be applied to predict the dynamic behavior of nonlinear systems, with potential applications in civil engineering, aerospace, and robotics. Overall, this study presents a promising approach for developing accurate models of complex structures with rigid or flexible components. The findings of this study may be valuable in designing structures that can withstand dynamic loads and vibrations.
Effect of ambient gas and crystal features on Doppler ultrasound twinkling of pathological mineralizations
Authors: Rokni Eric , Simon Julianna C.
Published: November 2023

Color Doppler twinkling on kidney stones and other pathological mineralizations is theorized to arise from stable microbubbles, which suggests twinkling will be sensitive to ambient gas. Here, lab-grown cholesterol, calcium phosphate, and uric acid crystals were imaged with ultrasound in water while varying oxygen, carbon dioxide, and nitrogen levels. Twinkling was found to increase on cholesterol in elevated oxygen, cholesterol and calcium phosphate in elevated carbon dioxide, and no crystals in elevated nitrogen. These results support the crevice microbubble theory of twinkling and suggest gases may be varied to enhance twinkling on some mineralizations.
Characterization of target gene regulation by the two Epstein-Barr virus oncogene LMP1 domains essential for B-cell transformation
Authors: Mitra Bidisha , Beri Nina Rose , Guo Rui , Burton Eric M. , Murray-Nerger Laura A. , Gewurz Benjamin E.
Published: November 2023

The Epstein-Barr virus (EBV) oncogene latent membrane protein 1 (LMP1) mimics CD40 signaling and is expressed by multiple malignancies. Two LMP1 C-terminal cytoplasmic tail regions, termed transformation essential sites (TES) 1 and 2, are critical for EBV transformation of B lymphocytes into immortalized lymphoblastoid cell lines (LCL). However, TES1 versus TES2 B-cell target genes have remained incompletely characterized, and whether both are required for LCL survival has remained unknown. To define LCL LMP1 target genes, we profiled transcriptome-wide effects of acute LMP1 CRISPR knockout (KO) prior to cell death. To then characterize specific LCL TES1 and TES2 roles, we conditionally expressed wildtype, TES1 null, TES2 null, or double TES1/TES2 null LMP1 alleles upon endogenous LMP1 KO. Unexpectedly, TES1 but not TES2 signaling was critical for LCL survival. The LCL dependency factor cFLIP, which plays obligatory roles in blockade of LCL apoptosis, was highly downmodulated by loss of TES1 signaling. To further characterize TES1 vs TES2 roles, we conditionally expressed wildtype, TES1, and/or TES2 null LMP1 alleles in two Burkitt models. Systematic RNAseq analyses revealed gene clusters that responded more strongly to TES1 vs TES2, that respond strongly to both or that are oppositely regulated. Robust TES1 effects on cFLIP induction were again noted. TES1 and 2 effects on expression of additional LCL dependency factors, including BATF and IRF4, and on EBV super-enhancers were identified. Collectively, these studies suggest a model by which LMP1 TES1 and TES2 jointly remodel the B-cell transcriptome and highlight TES1 as a key therapeutic target.

IMPORTANCE

Epstein-Barr virus (EBV) causes multiple human cancers, including B-cell lymphomas. In cell culture, EBV converts healthy human B-cells into immortalized ones that grow continuously, which model post-transplant lymphomas. Constitutive signaling from two cytoplasmic tail domains of the EBV oncogene latent membrane protein 1 (LMP1) is required for this transformation, yet there has not been systematic analysis of their host gene targets. We identified that only signaling from the membrane proximal domain is required for survival of these EBV-immortalized cells and that its loss triggers apoptosis. We identified key LMP1 target genes, whose abundance changed significantly with loss of LMP1 signals, or that were instead upregulated in response to switching on signaling by one or both LMP1 domains in an EBV-uninfected human B-cell model. These included major anti-apoptotic factors necessary for EBV-infected B-cell survival. Bioinformatics analyses identified clusters of B-cell genes that respond differently to signaling by either or both domains.