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This paper presents a numerical study of regular and hierarchical honeycomb structures subjected to out-of-plane impact loading. The specific energy absorption capacity of honeycomb structures via nonlinear explicit finite element analysis is investigated. The constructed finite element models are validated using experimental data available in the literature. The honeycomb structures are optimized by using a surrogate-based optimization approach to achieve maximum specific energy absorption capacity. Three surrogate models polynomial response surface approximations, radial basis functions, and Kriging models are used; Kriging models are found to be the most accurate. The optimum specific energy absorption value obtained for hierarchical honeycomb structures is found to be 148% greater than that of regular honeycomb structures.

NiTiHf-based shape memory alloys have been receiving considerable attention for high temperature, high strength and two-way shape memory applications since they could have transformation temperatures above 100°C, shape memory effect under high stress (above 500 MPa) and superelasticity above 100°C. Moreover, their shape memory properties can be tailored by microstructural engineering. However, NiTiHf-based alloys have some drawbacks such as low ductility and high slope in stress induced martensite transformation region. In order to overcome these limitations, studies have been focused on microstructural engineering by aging, alloying and processing. It has been revealed that microstructural control is crucial to govern the shape memory properties (e.g. transformation temperatures, matrix strength, shape recovery strain, twinning type, etc.) of NiTiHf-based alloys. A summary of the most recent improvements on selected NiTiHf-based systems is presented to point out their significant shape memory properties, effects of alloying, aging and microstructure of transforming phases and precipitates.

The results of investigations of the pyroelectric current in a layered TlInS2crystal doped with lanthanum are presented. A comparative analysis of the obtained results and data of photo-induced current transient spectroscopy has been performed. The revealed features of the contribution from electrically active defects to pyroelectric properties of the crystal have been discussed.

The high hardness and wear resistance levels of Alumina (Al2O3)-based ceramics make them excellent choices for incorporation into cutting tools that can be used to machine hardened steels. However, their poor fracture behaviour usually leads to catastrophic failures when they are used in these machining tasks. Thus, there is a need for an investigation that probes the effect of cutting parameters on the machining of hardened steels with Al2O3-based ceramic cutting tools and isolates a set of optimal values of cutting parameters. This paper is such a study. An experimental study that is guided by Taguchi’s techniques is performed to analyse the effects of three cutting parameters: cutting speed; feed rate; and depth of cut on two performance measures, flank wear and surface roughness. The robust optimal cutting parameters for each performance measure are reported.

Classical tail modelling is based on performing a relatively small number of limit-state calculations through Monte Carlo sampling, and then fitting a generalized Pareto distribution to the tail part of the data. The limit-state calculations that do not belong to the tail part are discarded. To reduce the amount of discarded data, this article proposes an efficient tail modelling procedure based on guiding the limit-state evaluations towards the sampling points that have high chances of yielding limit-state values falling into the tail region. The guidance of the limit-state evaluations is achieved through a procedure that utilizes limit-state approximation and distribution fitting. The accuracy of the proposed method is tested through a mathematical problem and four structural mechanics problems, and it is found that the accuracy of reliability estimations can be significantly increased compared to classical tail modelling techniques for the same number of limit-state function evaluations. In addition, it is also found that the improvement in accuracy can be traded off for reducing the number of limit-state evaluations.

Radial basis functions (RBFs) are approximate mathematical models that can mimic the behaviour of rapidly changing and computationally expensive simulations, such as finite element simulations for predicting automobile crash responses. The most popular way of selecting optimal RBF shape parameters is based on minimizing the globalcross-validation error (CVE). Solving this optimization problem may lead to the construction of globally accurate RBF models, but the shape parameters are assumed to be constant over the entire design space. On the other hand, having flexible shape parameters that can change over the design space may allow the local behaviour to be captured better, thereby improving the accuracy. Thus, optimizing the RBF shape parameters based on minimization of the pointwiseCVE rather than the global CVE is proposed in this paper. Three benchmark mathematical functions followed by an automobile crash problem are used to evaluate the effectiveness of the proposed method. It is found that the RBF models based on the minimum pointwise CVE outperform the RBF models based on the minimum global CVE.

Spontaneous spinal epidural haematoma (SSEH) is a neurosurgical emergency that requires early diagnosis and treatment. An 88-year-old man presented to the emergency department with complaints of weakness in the legs, walking deficit, incontinence and back pain for the last two days. He had been on warfarin therapy for 5 years for atrial fibrillation. There was no antecedent trauma. The neurological examination revealed hypoesthesia below the T6 level, anaesthesia below the T10 level and complete paraplegia of both lower extremities. The INR level was 7.81 on admission. Magnetic resonance imaging revealed a posterolateral epidural haematoma extending from T2 to L5. He was given fresh frozen plasma and vitamin K in the emergency department. Emergency thoracic and lumbar laminectomy was performed by neurosurgeons. The probability of SSEH should be investigated in any patient under anticoagulation therapy who presents with signs of spinal compression in the emergency department.

Spontaneous spinal epidural haematoma (SSEH) is a neurosurgical emergency that requires early diagnosis and treatment. An 88-year-old man presented to the emergency department with complaints of weakness in the legs, walking deficit, incontinence and back pain for the last two days. He had been on warfarin therapy for 5 years for atrial fibrillation. There was no antecedent trauma. The neurological examination revealed hypoesthesia below the T6 level, anaesthesia below the T10 level and complete paraplegia of both lower extremities. The INR level was 7.81 on admission. Magnetic resonance imaging revealed a posterolateral epidural haematoma extending from T2 to L5. He was given fresh frozen plasma and vitamin K in the emergency department. Emergency thoracic and lumbar laminectomy was performed by neurosurgeons. The probability of SSEH should be investigated in any patient under anticoagulation therapy who presents with signs of spinal compression in the emergency department.

For combined nail bed injuries and distal phalangeal fractures, fixation may be indicated when there is fracture instability and if a K-wire can be successfully placed in the fracture fragments. We determined the outcomes when these criteria were applied for patients with Allen type III injuries without substantial tissue loss. We retrospectively analyzed 57 patients who had surgery for nail bed injuries with distal phalangeal fractures between October 2017 and January 2020. All patients underwent anatomical nail bed repair, and some had fracture fixation, according to specific surgical criteria. We obtained data about demographic and clinical characteristics, postoperative radiographs, complications, range of motion, and satisfaction. To achieve our primary objective, we evaluated the patient population as a whole. The median follow-up was 12 months (range, 7–21). After 90 days, all 57 patients achieved satisfactory fracture union, 54 (95%) had excellent range of motion, and 54 (95%) were either satisfied or very satisfied with the outcome. Though 6 (10%) patients had residual fracture displacement, none had complications. In patients with Allen type III fingertip injuries without substantial tissue loss, anatomical nail bed repair and triage of patients to fixation or no fixation are likely to result in excellent functional outcomes and high patient satisfaction. However, fixation can neither be recommended nor rejected for these injuries based on this study alone.

Specific metabolic heat rates (Rq) and respiration rates (RCO2) of adult Harmonia axyridis Pallas, the multicolored Asian lady beetle, and Hippodamia convergens Guerrin-Manaville, the convergent lady beetle, were measured in isothermal calorimeters at 5°C intervals from 0 to 40°C. Anabolic rates and Rq/RCO2 ratios were calculated as functions of temperature from the calorespirometric data. The two species have similar heat and CO2 rates from 0 to 10°C, but both rates are higher for H. convergens at all other temperatures. Anabolic rates and Rq/RCO2 ratios indicated high-temperature stress in H. convergens at 40°C and at 35 and 40°C in H. axyridis . Anabolic rates and Rq/RCO2 ratios for the two species differed markedly from 15 to 30°C, where H. convergens had a higher anabolic rate and lower Rq/RCO2 ratio (i.e., greater metabolic efficiency) than H. axyridis . The data show that H. axyridis maximizes the anabolic rate, and therefore the biosynthesis rate, at low temperatures around 5°C and maximizes the catabolic rate at 25–30°C to support movement. In H. convergens , the optimum temperature range is the same for both biosynthesis (anabolic rate) and movement (catabolic rate), i.e., from 15 to 30°C. The ability of H. axyridis to more efficiently use periods of low temperature for development and reproduction and periods of mid-range environmental temperatures for searching for prey and feeding probably contribute to its competitive displacement of native North American coccinellid species.

The multicolored Asian lady beetle, Harmonia axyridis (Pallas), is displacing native coccinellid species in North America. To elucidate the mechanisms underlying this phenomenon, it is important to understand its physiological ecology. Hence, this study examined the temperature dependence of the respiratory physiology of this species. Calorespirometry was used to measure metabolic heat and CO2 production rates from second, third, and fourth instars; pupae; and adult beetles at temperatures from 0 to 40°C at 5°C intervals. Mass-specific respiration rates, in terms of either CO2 or heat production, increased with temperature, and, with the exception of pupae, decreased with increasing development. For all developmental stages, the results showed that below 10°C, CO2 was produced primarily from nonoxygen-consuming reactions. CO2 production gradually shifts more to oxygen-consuming reactions with increasing temperature, the fraction of CO2 from oxygen-consuming reactions reaching 0.5–0.7 at 40°C. Adults and second instars were stressed at 35°C and showed high mortality at 40°C, but these conditions were tolerated by all other stages studied. These data agree with field observations of the success of the multicolored Asian lady beetle in the temperature range from 15 to 25°C.

Characterizing temperature responses of predatory insects is an important part of understanding their life history, and is often necessary for predicting their potential as bio-control agents of herbivorous insects. To illustrate the power of current methods of calorespirometry in determining the response of energy metabolism to environmental variables, we used isothermal calorimetry to measure metabolic heat and CO2 production rates of convergent lady beetles (Hippodamia convergens, Guérin-Méneville) as a function of temperature. For comparison, CO2 production rates were also measured with an infrared gas analyzer. Anabolic rates and energy use efficiencies were calculated as functions of temperature from the calorespirometric data. For this species, both heat and CO2 rates are small (≈1 µW/mg and 8 pmol/s/mg, respectively) and essentially constant below 10°C, above which both rise approximately linearly up to ≈15 µW/mg and 50 pmol/s/mg at 40°C. The anabolic rate is approximately zero below 0°C, rises to a broad maximum of ≈7 µW/mg around 20°C, decreases above 25°C, and then exhibits an increase due to stress above 35°C. Energy use efficiency is roughly constant at ≈70% from 0 to 15°C, above which it decreases to ≈25% from 30 to 40°C. The beetles are predicted to be most successful in the temperature range from 10 to 35°C, with an optimum from 15 to 25°C. These conclusions agree with results from behavioral studies, but the calorespirometric methods are much faster, less labor intensive, and can be applied to any stage of development.

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