Changes In Configuration Research Articles

An experimental parametric study assessing the effect of a certain initial geometric imperfection on cylinder buckling

Given the sensitivity of axially-loaded cylinder buckling to geometric imperfections, the advent of additive manufacturing provides a compelling platform to assess subtle changes in initial configuration from an experimental perspective. The cylindrical form is ubiquitous in many load-bearing contexts, from soda cans to submarines to rocket fuel tanks. Despite the relative simplicity of the shape, it is striking how the assessment of buckling loads continues to pose strong challenges to the designers of these load-bearing components, often in a situation where weight-saving is a key constraint. Furthermore, this type of buckling typically corresponds to a sudden, severe, catastrophic event, and in addition to posing serious consequences in practice, this also presents challenges for those conducting high-fidelity experiments, especially in terms of repeatability. Any conditions that deviate from a pristine cylindrical shape, and purely axial loading, are the root-cause of the buckling variability. Typically, the slight deviations from the pristine (perfect) conditions are somewhat random and unpredictable in nature. 3D-printing now provides the experimentalist with the ability to produce cylindrical specimens to a very high degree of geometric fidelity, thus allowing a degree of control of the form of subtle geometric imperfections. This paper focuses attention on a specific form of deviation from a pristine cylindrical shape, in which the longitudinal sides follow a mild cosine wave form. The amplitude of this shape is varied (in both directions, i.e., inwards and outwards), and its effect on both the buckling load and buckling mode shape assessed experimentally, using the outcome of finite element analysis as a guide.

A 31-year follow-up of those with occult spinal dysraphism, who underwent spinal cord untethering: Lower urinary tract function, skin stigmata, fertility, and work participation.

This study evaluated patients with occult spinal dysraphism who underwent spinal cord untethering. Twenty-four patients who visited us between 1983 and 2000 were followed-up for a mean duration of 31 years. We studied their lower urinary tract function, skin stigmata, fertility, and work participation. Questionnaires sent in 2022 revealed that 5 patients had normal voiding (Group A) and 19 patients had abnormal voiding (Group B). Groups A and B underwent spinal cord untethering at a mean age of 5.7 and 13.0 years, respectively, showing a significant statistical difference (p = 0.036). After spinal cord untethering, the number of patients with detrusor normoactivity increased from 0 to 5, i.e., 3 of 6 with detrusor overactivity (50%), 1 of 2 not examined, and 1 of 5 not known. Patients with detrusor underactivity also increased from 11 to 19. Severity of incontinence in the International Consultation on Incontinence Questionnaire-Short Form resulted in a mean value of 2.4 in Group A, which was significantly superior to the mean value of 9.1 in Group B (p = 0.004). Fourteen patients (58.3%) were married and had 21 healthy children. A majority of patients have had full-time jobs. A variety of skin stigmata were present in the lumbosacral region, and changes in vesico-urethral configurations were observed during a video-urodynamic study. Our study identified that the early timing of spinal cord untethering performed in neonates or infants and detrusor overactivity prior to untethering surgery are important factors in achieving normal bladder function.

How to Choose the Best Optogenetic Tool for Your Research

All-optical methods that provide deeper understanding of neural activity are currently being developed. Optogenetics is a biological technique useful to control neuronal activity or life phenomena using light. Microbial rhodopsins are light-activated membrane proteins used as optogenetic tools. Microbial rhodopsins such as channelrhodopsin2 (ChR2) consist of seven-pass transmembrane proteins with a covalently bound retinal. Light absorption is followed by photoisomerization of the all-trans retinal to a 13-cis configuration and subsequent conformational changes in the molecule, with consequent permeability of the channel structure to ions. Recent studies have reported the discovery of microbial rhodopsins with novel functions. Microbial rhodopsin diversity has also increased. We describe the characteristics of microbial rhodopsins used as optogenetic tools and the latest research in this domain.

Preparation and Properties of Multi-Responsive Liquid Crystalline Poly(urethane-acrylate)s and Its Composite Membranes.

In this work, a kind of side chain liquid crystalline poly(urethane-acrylate)s was synthesized by free polymerization based on self-made liquid crystalline monomers, and a series of liquid crystalline polyurethane/shape memory polyurethane composite membranes were prepared by electrospinning. The synthesized liquid crystalline poly(urethane-acrylate)s have excellent thermal stability. Due to the regular arrangement of azobenzene on the side chains, polymers can rapidly undergo a photoinduced transition from trans-isomerism to cis-isomerism in THF solution and restore reversible configurational changes under visible light. The composite membranes prepared by electrospinning can also undergo photoinduced deformation within 6 s, and the deformation slowly returns under visible light. Meanwhile, the composites have shape memory, and after deformation caused by stretching, the membranes can quickly recover their original shape under thermal stimulation. These results indicate that the composites have triple response performances of photoinduced deformation, photo-, and thermal recovery.

Host–guest complexation‐induced chirality switching of pillararenes by perylene diimide‐based hexagonal metallacages

AbstractChirality in confined nanospaces has brought some new insights into chirality transfer, amplification, and chiroptical properties. However, chirality switching, which is a common phenomenon in biological systems, has never been realized in confined environments. Herein, we report a type of hexagonal metallacages that shows good host–guest interactions with ethoxy pillar[5]arene and pillar[6]arene, as confirmed by single‐crystal X‐ray analysis. Importantly, when a chiral pillar[5]arene‐based molecular universal joint (MUJ) is used as the guest, the host–guest complexation would drive the alkyl ring of the MUJ flip from outside to inside the cavity of its pillar[5]arene unit, which enables the configuration change along with the chirality inversion of the MUJ. Moreover, the host–guest complexation facilitates the chirality transfer from guests to hosts, giving circularly polarized luminescence to the system. This study provides a unique metallacage‐pillararene recognition motif for the chirality switching of planar chiral pillararenes, which will promote the construction of host–guest systems with tunable chirality for advanced applications.

Key Actions to Enable Automation for Mobile Network Security Operations

Over time, the landscape of Cyberspace surrounding Internet Service Providers (ISPs) has undergone enduring transformations. Notably, mobile networks, integral to contemporary societal infrastructure, consistently encounter evolving cybersecurity threats and risks. ISP processes have adapted with a persistent focus on optimizing network performance and availability, yet the challenges emerge from a laborious and protracted network change management process, hindering the practical automation of network security. Addressing the rightful demand for the highest level of security from mobile network users, our research question probes: "How can we intensify the emphasis on network security and facilitate the automation of network security operations?" To delve into this, we conducted extensive interviews with ISPs globally, affirming the inherent difficulty in automating security operations. The findings categorize challenges into three domains: Security Culture, Operational Processes, and Tools. Cultivating a security culture demands a pivotal commitment to change from top management, coupled with dedicated time and resources. Essential to this is the enhancement of security competence, extending beyond specialists to encompass network engineering staff. Robust network security not only safeguards against threats but significantly influences various business processes. Initiating a secure network requires ISPs to articulate explicit security requirements during the network procurement process, exerting pressure on vendors to fortify systems with a security-by-design approach at the factory. Critical to this is the secure deployment of networks, integrating comprehensive network hardening during the build phase. However, findings indicate a prevalent oversight where network security configuration changes are often neglected or deprioritized in favor of network performance. Achieving a harmonious balance between security and performance necessitates a predefined agreement on a network security configuration baseline. This collaborative effort involves network security specialists and competent network engineers. To effectively monitor and enforce network security configuration, ISPs require automation-enabled tools with the predefined baseline, offering capabilities for monitoring and enforcing network assets. In conclusion, our research emphasizes the imperative need for a paradigm shift in organizational culture, operational processes, and tool utilization to enhance the focus on network security and enable the critical automation of network security operations within the ever-evolving landscape of Cyberspace.

What controls structural variations along the Zagros Collision Zone? Insights from geophysical observations and thermo-mechanical modelling

The Zagros Collision Zone is a complex tectonic region formed as a consequence of the collision between Arabia and Eurasia after the subduction of the Neo-Tethys ocean. The NW-SE striking Zagros orogen consists of the following parallel tectonic units (from SW to NE): Zagros Fold and Thrust Belt (ZFTB), Sanandaj–Sirjan Metamorphic Zone (SSZ), and Urumieh–Dokhtar Magmatic Arc (UDMA). In this study, we perform a combined analysis of recent geophysical data, revealing pronounced differences in the crustal and lithospheric structure along the Zagros Mountains. The northwestern sector shows a fairly uniform crustal thickening across the broad symmetric orogen from the ZFTB to the UDMA. In contrast, in the central Zagros, the transition from a relatively narrow zone of high elevations and high-frequency relief in the ZFTB to a smoother surface topography of the SSZ and UDMA occurs with an abrupt increase in Moho depth below the SSZ. The last observation has recently been interpreted as a result of “relamination” process, where the felsic upper crust of the Arabian plate underthrust the mafic crust of the Iranian plate. We present geodynamic numerical models of crustal relamination during continental collision and compute static gravity field of the resulting structures. We show that oblique closure of the Neo-Tethys affects lateral variations in the style and extent of crustal relamination, which control the observed along-strike changes in crustal configuration and orogen altitude. In particular, a narrow and higher orogen (as in the central Zagros) develops in the experiments with a young and wide oceanic plate, whereas an old and narrow subducting plate tends to form a broad and lower topography (as in the northwestern Zagros). This is geometrically consistent with the progressive closure of the Neo-Tethys from NW to SE during the oblique continental collision between Arabia and Eurasia.

Prediction of cavity inception speed and underwater radiated noise of a full-scale marine propeller based on a cavitation tunnel model test

Propeller cavitation is a dominant source of underwater radiated noise (URN) from shipping, and the appropriate evaluation of propeller noise mitigation measures is important for ecological ship design. In this study, a model test procedure and scaling method to predict the full-scale URN level from hydrodynamic noise sources were introduced. The cavity size based on the empirical vortex model was considered in the proposed scaling method for a quiet cruise condition with isolated tip vortex cavitation. This relation provides information on the equivalent cavitation number for the model test to have the same relative radius as that of the full-scale tip vortex cavitation. The alternative test cavitation number can also be chosen as close as possible to the point that gives the equivalent tip vortex cavity size if sheet cavitation exists in the condition for the equivalent cavity size. In this case, additional noise scaling should be performed using the ratio of the tip vortex cavity radii. The new scaling exponent introduced in this study varies according to the distance from the cavitation inception condition and shows a decreasing trend from the value at the inception condition as the equivalent cavitation number for the model test decreases. The scaled URN levels based on the proposed method showed reasonable agreement with the measurement results of a full-scale ship. Finally, the noise reduction effect of the specially designed wake control fin and propeller was investigated through a comparative model test following the proposed scaling strategy, and significant noise reductions were observed with changes in the design configuration.

Configurational changes of ruptured intracranial aneurysms at the window between pre-operative CTA and the definite clipping surgery

Background: Ruptured intracranial aneurysms may face configurational changes in size and shape resulting from extreme weakness in their wall. These configurational changes are associated with an amplified risk of rupture and surgical challenges as these aneurysms have proven to be unstable. However, to our knowledge, no previous studies have addressed the issue of configurational aneurysmal changes between the patient’s presentation (radiological images) and intraoperative findings. This paper aims to compare aneurysmal size and shape between pre-operative Computed tomography angiography and intraoperative lesion characteristics in a cohort of patients presented to our centre. Methods: A retrospective analysis was performed on cases admitted to the Neurosurgery Teaching Hospital in Baghdad, Iraq, and underwent microsurgical clipping of ruptured aneurysms. Their records were checked for aneurysmal configurational changes by comparing pre-operative radiological images and intra-operative findings. Results: Of the 275 patients, 5 cases were enrolled with aneurysmal configurational changes. Three of them were females, and two were males. The pre-operative aneurysmal shapes based on Computed tomography angiography were (3 unicyst and two conical shapes) and the range of aneurysmal size was (7-11 mm) with a mean of 9 mm. Compared to intra-operative findings, there were total aneurysmal shape changes (connected cyst in 4 patients and spherical aneurysm in one patient). The range of aneurysmal size was (7-11 mm) with a mean of 9 mm. Conclusion: Intracranial aneurysms may undergo configurational changes through the time between pre-op imaging and surgery; early detection of these changes may ensure optimal management of such cases.

Attitude and position control for formation flying of space robots equipped with a robotic manipulator

This paper presents a novel six degree-of-freedom guidance and control algorithm for free-flyer robots equipped with a robotic manipulator operating on the International Space Station. The proposed algorithm combines a sliding mode controller for rotational motion and a model predictive controller for translational motion. A novel prediction-twisting sliding mode controller (PT-SMC) is introduced to stabilize configuration changes induced by the manipulator and correlated disturbances and to achieve a trade-off among control law flexibility, robustness, and accuracy. The proposed PT-SMC is shown to have improved stability compared to a first-order sliding mode controller. Model predictive control is investigated as a position controller to achieve formation flight between multiple free flyers in a constrained environment, and a leader–follower approach is used to move a triangular formation of robots. A control allocation problem is solved to address the subdivision of attitude and position controls between twelve thrusters. Simulation results of multiple robots approaching a target object demonstrate the improved performance of the proposed control approaches.

Reduced Training Data for Laser Ultrasound Signal Interpretation by Neural Networks

The performance of machine learning algorithms is conditioned by the availability of training datasets, which is especially true for the field of nondestructive evaluation. Here we propose one reconfigurable specimen instead of numerous reference specimens with known, unchangeable defect properties, which are usually complicated to fabricate. It consist of a shape memory polymer foil with temperature-dependent Young’s modulus and ultrasound attenuation. This open a possibility to generate a reconfigurable defect by projecting a heating laser in the form of a short line on the specimen surface. Ultrasound is generated by a laser pulse at one fixed position and detected by a laser vibrometer at another fixed position for 64 different defect positions and 3 different configurations of the specimen. The obtained diversified datasets are used to optimize the neural network architecture for the interpretation of ultrasound signals. We study the performance of the model in cases of reduced and dissimilar training datasets. In our first study, we classify the specimen configurations with the defect position being the disturbing parameter. The model shows high performance on a dataset of signals obtained at all the defect positions, even if trained on a completely different dataset containing signals obtained at only few defect positions. In our second study, we perform precise defect localization. The model becomes robust to the changes in the specimen configuration when a reduced dataset, containing signals obtained at two different specimen configurations, is used for the training process. This work highlights the potential of the demonstrated machine learning algorithm for industrial quality control. High-volume products (simulated by a reconfigurable specimen in our work) can be rapidly tested on the production line using this single-point and contact-free laser ultrasonic method.

Mechanical Properties of Polydiacetylene Multilayers Studied by AFM Force Spectroscopy.

The blue-to-red chromatic phase transition of polydiacetylene (PDA) is accompanied by the twist and rearrangement of its side chains, which results in shortening of the conjugation length in the backbone. However, how these morphological changes affect its mechanical properties remains elusive. In this work, force spectroscopy mapping by atomic force microscopy was employed to quantify mechanical parameters of PDA thin films such as breakthrough force and Young's modulus at the monomer, blue, and red phases during the chromatic transition. We found that the breakthrough force increased by 113% and Young's modulus decreased by 21% during the blue-to-red transition, highlighting that the subtle change in the side-chain configuration has a dramatic impact on its mechanical properties.

The impact of changes in scale configuration on the gangsa instrument of the Bhavana Ethnic Mataram as an Indonesian music innovation

The impact of changes in scale configuration on the gangsa instrument of the Bhavana Ethnic Mataram as an Indonesian music innovation

Label-free detection of platelet-derived growth factor-BB via liquid crystal/aqueous interface functionalized using a double-stranded DNA probe

A liquid crystal (LC)-filled transmission electron microscopy (TEM) grid cell coated with cationic surfactant octyltrimethylammonium bromide (OTAB) and adsorbed with a double-stranded deoxyribonucleic acid (dsDNA) probe at the LC/aqueous interface (TEMOTAB/DNA) was utilized for the highly specific detection of platelet-derived growth factor (PDGF-BB). Upon adsorption of the OTAB-coated 4-cyano-4′-pentylbiphenyl (5CB) on the TEM grid (TEMOTAB) and subsequent adsorption of the dsDNA probe, a homeotropic orientation was observed. Subsequently, the TEMOTAB/DNA biosensor was exposed to PDGF-BB, which induced a homeotropic-to-planar configurational change in 5CB, as observed using polarized optical microscopy with crossed polarizers. The optimized adsorption density of the dsDNA probe facilitated the detection of 2.63 pg mL−1 PDGF-BB in the detection range of 5–200 pg mL−1. Remarkably, this LC-based biosensor discriminated PDGF-BB from bovine serum albumin, immunoglobulin G, hemoglobin, carcinoembryonic antigen, epidermal growth factor, PDGF-AA, and PDGF-AB. The application potential of this sensor was further demonstrated by its effective performance in detecting PDGF-BB in both human serum and synthetic urine samples. Because of its high specificity, sensitivity, and label-free detection capabilities, this biosensor has potential applications in cancer detection.

Adaptive differential steering strategy for distributed driving unmanned ground vehicle with variable configurations based on modified localized modelling sliding mode control

When performing complex tasks such as position transfer and material transportation, the distributed driving unmanned platform with variable configurations needs to address the challenge of multi-wheel cooperative torque distribution control to achieve high-performance differential steering and enhance vehicle dynamics. The configuration change will impact the dynamic performance of the unmanned platform, posing a challenge to the performance of the existing control strategy based on mathematical model development. In order to address the aforementioned issues, this paper analyzes the impact of changes in vehicle configuration on steering gain and proposes a hierarchical adaptive differential steering strategy based on variable vehicle configurations. Firstly, the response characteristics of the yaw angle relative to the active yaw moment under the influence of changes in wheelbase and tread are analyzed. Based on this analysis, two structural modes, maneuverable and balanced, are selected. Secondly, a localized-modelling sliding mode control method with an extended state observer is proposed to estimate the desired yaw moment in the upper controller, considering the motor's execution delay. Then, the lower controller optimizes the torque of each wheel in real-time using the whale optimization algorithm. It aims to optimize tire energy dissipation and tire load rate while ensuring driving stability and achieving differential steering. Finally, through co-simulation and experiments on a scaled prototype, the reliability of the dynamics theory and the superiority of the control algorithm are validated. This optimization has led to significant improvements in the tire dissipation energy index and tire load rate index.

Aqueous size exclusion chromatography applied to polymer analysis: experimental conditions and molecular weight calibration curves

Aqueous mode size exclusion chromatography (SEC) was employed for the analysis and construction of molecular weight (MW) calibration curves of three water-soluble polymers, namely, polyethylene glycol, polyethylene oxide, and polyacrylic acid sodium salt. Several calibration curves were obtained, varying chromatographic conditions such as columns arrangement, ionic strength, temperature and pH, in addition trends in polymeric chromatographic behavior were examined. The variation in SEC distribution coefficients at different temperatures was found to be below 10 %, indicating that the studied polymers follow an ideal SEC mechanism under the tested conditions. Thus, differences in chromatographic behavior were ascribed to changes in polymer configuration induced by media and/or temperature. These variations in morphology were consistent with the observed SEC behavior.Regarding MW calibration, polynomial regression models ranging from first to fifth order were applied, and the most adequate ones were selected based on their fit and prediction capabilities. Third order polynomials were the preferred models for polyethylene glycol and polyacrylic acid sodium salt, independently of chromatographic conditions. Meanwhile for polyethylene oxide, either third or fifth-order polynomial models were optimal depending on the chromatographic conditions. All the selected regression models presented coefficients of multiple determination (R2) above 0.990, while achieving relative errors of prediction (REP%) in MW ranging from 0.3 to 4 % for cross-validation.

Enterprise cloud resource optimization and management based on cloud operations

The so-called automated operation and maintenance refers to a large number of repetitive tasks in daily IT operations (from simple daily checks, configuration changes and software installation to organizational scheduling of the entire change process) from manual execution in the past to standardized, streamlined and automated operations. This article delves into the realm of enterprise cloud resource optimization and management, leveraging automated operations (autoOps) as a fundamental strategy. As industries like banking witness exponential growth and innovation in IT systems, the complexity of managing resources escalates. Automated operations have emerged as a critical component, transitioning from manual interventions to encompass standardization, workflow optimization, and architectural enhancements. Through real-world deployments and theoretical frameworks, it elucidates effective strategies for optimizing and governing enterprise cloud resources, thereby enhancing efficiency, security, and resilience in IT operations.

Reconfigurable origami-inspired multistable metamorphous structures.

Origami-inspired metamorphous structures can adjust their shapes and mechanical behaviors according to operational requirements. However, they are typically composed of nonrigid origami, where required facet deformation complicates actuation and makes them highly material dependent. In this study, we present a type of origami metamorphous structure composed of modular bistable units, each of which is a rigid origami. The elasticity within the origami creases and switching of mountain and valley crease lines enable it to have bistability. The resultant metamorphous structure has multistability, allowing it to switch among multifarious configurations with programmable profiles. This concept was validated by potential energy analysis and experiments. Using this concept, we developed a robotic limb capable of both lifting and gripping through configuration changes. Furthermore, we used the origami units to construct a metamaterial whose properties could change with the variation of configurations. These examples demonstrate the concept's remarkable versatility and potential for many applications.

Enterprise cloud resource optimization and management based on cloud operations

The so-called automated operation and maintenance refers to a large number of repetitive tasks in daily IT operations (from simple daily checks, configuration changes and software installation to organizational scheduling of the entire change process) from manual execution in the past to standardized, streamlined and automated operations. This article delves into the realm of enterprise cloud resource optimization and management, leveraging automated operations (autoOps) as a fundamental strategy. As industries like banking witness exponential growth and innovation in IT systems, the complexity of managing resources escalates. Automated operations have emerged as a critical component, transitioning from manual interventions to encompass standardization, workflow optimization, and architectural enhancements. Through real-world deployments and theoretical frameworks, it elucidates effective strategies for optimizing and governing enterprise cloud resources, thereby enhancing efficiency, security, and resilience in IT operations.

Memristors Based on Ni(II)‐tetraaza[14]annulene Complexes: Toward an Unconventional Resistive Switching Mechanism

AbstractIn this work, a family of Ni‐based dibenzotetraaza[14]annulene (dtaa) complexes are investigated for their application in memristors (memory resistors). A series of four Ni(II) complexes with different peripheral substituents of the dtaa ligand are successfully synthesized. Based on these compounds, two‐terminal thin‐film devices are fabricated in planar architecture. Four metals with different work functions are tested: Mg, Cu, Ni, and Au. It is demonstrated that ITO|[Ni(Me4dtaa)]|Cu devices show hysteretic behavior and offer stable, robust, and reproducible switching between high‐ and low‐resistive states. An in‐depth spectroscopic characterization of the Ni complex is performed, using radiation from infrared, through visible and ultraviolet, to tender X‐rays. Operando X‐ray fluorescence spectroscopy is used to monitor redox and structural changes upon the polarization of the studied memristor with the external electric field. Density functional theory calculations are used to better understand the electronic structure of the studied material, as well as structural rearrangement after electron injection that may be responsible for the modulation of electric conductivity. Finding a unique case of filamentary‐type resistive switching involving redox reactions of stationary molecules within a molecular solid is postulated. Yet, the formation of these filaments is not related to any significant configurational changes at the atomic scale.