A dual-band sensor based on a planar rectangular cavity loaded with pairs of improved planar resonator is used to measure the permittivity difference of liquids with a small volume (<inline-formula> ...<tex-math notation="LaTeX">2.5~\mu \text{l} </tex-math></inline-formula>). The planar cavity is connected by two microstrip transmission lines, constituting a two-port device with two branches. A pair of interdigital capacitor (IDC)-based split ring resonator (SRR) is coupled to the middle part of each branch. The distance between the IDC-SRRs is large, and their coupling can be neglected. Thus, two resonance frequencies are produced (4.15 and 9.18 GHz). One frequency is generated from the resonance of the two IDC-based SRRs (4.15 GHz), whereas the other results from the coupling of the rectangular cavity and the two IDC-based SRRs (9.18 GHz). Frequency splitting is used to detect changes in the dielectric characteristics of the liquids. If the two branches (IDC-based SRRs) of the proposed sensor are placed on the same liquid, only two resonance frequencies are obtained. When two different liquids are loaded by the sensor, the resonance frequency will be split into four. A planar rectangular cavity is used instead of a splitter configuration to motivate the two IDC-SRRs. This novel design affords a dual-band miniaturized sensor.
•A 3-D constitutive modeling of SMAs using microplane formulation in a thermodynamically-consistent framework is proposed.•The new formulations in a thermodynamic framework guarantee the second law ...of thermodynamic.•The modified model has been verified against experimental results in various loading conditions.•A research community in the area of constitutive modeling and experimental characterization of SMAs.
In microplane theory, it is assumed that a macroscopic stress tensor is projected to the microplane stresses. It is also assumed that 1D constitutive laws are defined for associated stress and strain components on all microplanes passing through a material point. The macroscopic strain tensor is obtained by strain integration on microplanes of all orientations at a point by using a homogenization process. Traditionally, microplane formulation has been based on the Volumetric–Deviatoric–Tangential split and macroscopic strain tensor was derived using the principle of complementary virtual work. It has been shown that this formulation could violate the second law of thermodynamics in some loading conditions. The present paper focuses on modeling of shape memory alloys using microplane formulation in a thermodynamically-consistent framework. To this end, a free energy potential is defined at the microplane level. Integrating this potential over all orientations provides the macroscopic free energy. Based on this free energy, a new formulation based on Volumetric–Deviatoric split is proposed. This formulation in a thermodynamic-consistent framework captures the behavior of shape memory alloys. Using experimental results for various loading conditions, the validity of the model has been verified.
A soft and highly directive, proximity-coupled split-ring resonator fabricated with a liquid alloy, copper and polydimethylsiloxane (PDMS) is presented. The same was designed for sensing osteogenesis ...of calvarial bone. As dielectric properties of bone grafts in ossifying calvarial defects should change during the osteogenesis process, devices like this could monitor the gradual transformation of the defect into bone by differentiating changes in the dielectric properties as shifts in the resonance frequency. Computational Software Technology (CST) Microwave Studio®-based simulation results on computational head models were in good agreement with laboratory results on head phantom models, which also included the comparison with an in-vivo measurement on the human head. A discussion based on an inductive reasoning regarding dynamics’ considerations is provided as well. Since the skin elasticity of newborn children is high, stretching and crumpling could be significant. In addition, due to typical head curvatures in newborn children, bending should not be a significant issue, and can provide higher energy focus in the defect area and improve conformability. The present concept could support the development of soft, cheap and portable follow-up monitoring systems to use in outpatient hospital and home care settings for post-operative monitoring of bone healing after reconstructive surgical procedures.
•The deformation process of foamed concrete goes through elastic stage, compaction stage and failure stage successively.•The dynamic mechanical properties of foamed concrete exhibit a significant ...strain rate enhancement effect and density dependence.•The damage characteristics are analyzed quantitatively by fractal calculation of the fracture.•The failure patterns of foamed concrete are consistent with the fractal characteristics.
As an energy-saving and environmentally friendly building material, foamed concrete has been widely applied for construction against impact loading. To investigate the dynamic mechanical properties and damage characteristics of lightweight foamed concrete under impact loading, a series of impact experiments are carried out on foamed concrete with densities of 300 kg/m3, 450 kg/m3 and 700 kg/m3 under a strain rate range of 60 s−1–250 s−1 by using a split Hopkinson pressure bar (SHPB) device. The stress-strain relationship, elastic modulus, peak stress and dynamic increase factor are discussed and analyzed in detail. The results show that the dynamic mechanical properties of the material exhibit a significant strain rate enhancement effect and density dependence. In addition, the damage characteristics are analyzed quantitatively by fractal calculations of the fracture. The fractal dimension increases markedly with increasing strain rate, and the maximum is 3.57, which indicates that the overall damage is related to the strain rate. For the three different foamed concrete specimens under a strain rate of approximately 130 s−1, the fractals present a transition behavior. The failure patterns of the foamed concrete are consistent with the fractal characteristics.
•Enhancements to split Hopkinson pressure bar technique for testing high-strength concrete.•Rate sensitivity determined for HSCs; similar DIF values for C60 and C80, but a much lower DIF for ...C110.•CEB-FIP model (2010) is inadequate for estimating rate sensitivity for HSCs, especially C110.•FE simulation confirms that the rate dependence determined from dynamic tests represents actual material behaviour.•Influence of radial inertia on compressive strength obtained from SHPB tests was examined via FE simulation.
An experimental investigation into the dynamic compressive response of high-strength concrete with three different strengths – 60MPa, 80MPa and 110MPa, denoted by C60, C80 and C110, respectively – was undertaken. Concrete specimens were subjected to quasi-static and dynamic compression, using a Denison Universal Testing Machine and a Split Hopkinson Pressure Bar (SHPB) device, and the effects of strain rate on their mechanical properties (e.g. stress-strain relationship, compressive strength) examined. Significant rate dependence was observed for all three concretes – i.e. the compressive strength increases with strain rate and the dynamic strength is much higher than the static value; C60 and C80 exhibited similar rate sensitivity, while C110 displayed a relatively noticeably lower rate dependence. The rate sensitivity was quantified via a Dynamic Increase Factor (DIF, the ratio between the dynamic and static strength), and this was compared with predictions by the CEB-FIP 2010 equation, commonly utilised to estimate rate sensitivity for normal strength concrete. The comparison indicates that the model is not suitable for high-strength concrete, as it predicts a sharper rise in rate-sensitivity, and the mismatch increases with concrete strength, becoming notably significant for C110. Interpretation of rate dependence of concrete materials based on SHPB test results, as to whether it is an intrinsic material property, or generated primarily by radial inertia, was examined by finite element modelling of SHPB tests. Concrete material properties were taken to correspond to a concrete damaged plasticity model, and the quasi-static stress-strain response, coupled with the Dynamic Increase Factor determined from dynamic tests, was utilised. The simulation results correlated closely with experiments, in terms of strain gauge signal histories in the SHPB loading bars, indicating that for the strain rate range investigated (30–110 s−1), radial inertia is not significant, and the rate dependence observed is attributable to material response.
The split quaternionic Schrödinger equation ∂∂t|f〉=−A|f〉 plays an important role in split quaternionic mechanics, in which A a split quaternion matrix. This paper, by means of a real representation ...of split quaternion matrices, studies problems of split quaternionic Schrödinger equation, and gives an algebraic technique for the split quaternionic Schrödinger equation. This paper also derives an algebraic technique for finding eigenvalues and eigenvectors of a split quaternion matrix in split quaternionic mechanics.
Several studies have reported disproportionate wasting of the flexor muscles of the lower limbs (LL) compared to the extensors in patients with amyotrophic lateral sclerosis (ALS). However, these ...studies have involved small sample sizes (n 〈100), and their findings have been inconsistent. Thus, it remains uncertain whether a distinct pattern of LL muscle weakness is specific to ALS.
To investigate the muscle weakness pattern in the LL at the knee, ankle, and toes in a large cohort of ALS patients and evaluate the relationship between the pattern of muscle strength and the extent of upper (UMN) and lower (LMN) motoneuron impairment.
The strength of flexor and extensor muscle was evaluated in 1250 legs of newly diagnosed ALS patients at the knee, ankle, and foot toes. UMN and LMN burden were assessed using validated scores. Within-subjects ANOVA considering the type of muscle (flexor/extensor) and anatomical sites (knee/ankle/toes) and mixed-factorial ANOVA were conducted to explore the impact of UMN and LMN impairments on the muscle weakness pattern.
Muscle strength showed a significant decline from proximal to distal regions. Indeed both flexor and extensor muscles at the knee outperformed those at the ankle and toes. Within each site, extensor muscles exhibited less strength than flexor, except at the knee. Patients with heightened UMN impairment showed a more marked difference between flexors and extensors within each site, with extensor muscles being more compromised at the ankle and toes. Higher LMN impairment corresponded to a more pronounced weakness in flexor muscles at the ankle and toes compared to those at the knee.
The extensor muscle at the knee and the flexors at the foot and toes displayed relative resistance to ALS disease. UMN impairment amplified the differences between flexor and extensor muscles within each site, while LMN impairment demonstrated a clear distal-to-proximal vulnerability.
•Knee extensors and foot/toe flexors show relative preservation in ALS disease.•UMN damage increases flexor/extensor muscle differences at each site.•LMN damage shows a clear distal-to-proximal muscle weakness pattern.
Harary and Norman introduced the line graph L(G) . We introduced the legendary domination number by combining the domination concept both in graph and its line graph. In this paper, the split ...domination property is studied along with the legendary domination concept. Hence the split legendary dominating set is introduced and the corresponding split legendary domination number is defined for the line graph L(G). Also, the graph theoretical parameters are studied in terms of elements of G and its relationship with other domination parameters are presented.
There are many situations in industrial experimentation where departures from the fundamental principles of experimentation-randomization, replication, and local control of error-are commonplace. For ...instance, complete randomization is not always feasible when factor level settings are hard, impractical, or inconvenient to change, or when the resources available to execute the experiment under homogeneous conditions are limited. These restrictions in randomization lead to split-plot designs. Often, we are also interested in fitting higher-order statistical models, which calls for response surface split-plot designs. In this article we explore the systematic construction of a class of response surface split-plot design we call response surface Cartesian product split-plot designs. This collection of design alternatives offers an effective and efficient addition to the split-plot design repertoire available currently in the engineering, manufacturing, quality control, and test and evaluation communities. These designs are generally competitive in size relative to other standard designs, easy to construct, can be executed sequentially, have good coverage, low prediction variances, minimal aliasing between the model terms, and are suitable for cuboidal and spherical regions of the factor space. When evaluated with well-accepted design evaluation criteria, response surface Cartesian product split-plot designs perform as well as designs that have been standards in the response surface split-plot methodology community such as equivalent estimation designs, minimum whole plot designs, and optimal designs.
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