In this paper, Crush force efficiency (CFE), Specific Energy Absorption (SEA), Energy Absorption per Crush Length (E
cl
), Maximum and average crush forces of straight and grooved tapered thin-walled ...tubes with various cross-section shapes (circle, ellipse, square, rectangle, hexagon, and octagon) have been studied. The effects of taper, the groove (as initiator) and their interaction have been presented in the current study using Finite Element Method as a numerical method. The tubes have the same volume, height, average cross-section area, thickness and material and have been subjected to axial and oblique dynamic loading. The results of simulations show that the section's geometry, taper and groove addition have a significant effect on energy absorption behavior and the hexagon cross section have better energy absorption behavior compared with other considered geometries. On the other hand, it was found that the behavior of these structures could improve against dynamic axial and oblique impact loading with the cost-effective geometry modifications. These results could help to improve and choose appropriate energy absorber structure based on desirable crush force and energy absorbing characteristics.
This work proposes and investigates a PCM based optical modulator tailored for 2.1 μm wavelength operation, which finds diverse potential applications in medicine, wind speed sensing, water vapor ...detection, and carbon dioxide monitoring. We propose and simulate a SiC-core waveguide on SiO
2
substrate employing VO
2
as an integrated phase change cladding layer to achieve optical modulation. The optimized SiC core thickness is 400 nm based on modeling the SiO
2
/SiC/SiO
2
waveguide structure. The waveguide structure can achieve optical switching by transitioning the phase of VO
2
cladding between its metallic and insulating phases. Key optical parameters including the complex effective index, confinement factor, and normalized effective index are calculated as a function of VO
2
thickness, ridge width, and wavelength for both TE and TM polarizations. The results indicate that for TM-polarized light, modulation of the optical signal can be achieved by electrically tuning the VO
2
phase, yielding electro-absorption modulation over a 1 μm device length. Simulations demonstrate a propagation length of 2.1539 μm in the transparent insulating phase of VO2 and 0.1552 μm when transitioned to its opaque metallic phase, indicating strong optical absorption modulation suited for various applications. With customized engineering at a novel wavelength, this pioneering SiC-VO
2
device holds great promise to further progress optical modulation capabilities for an array of applications across science and industry.
This paper presents a model that has less constraints than similar models and explains the collapse phenomenon in any desired order of geometrical asymmetries and in the presence of symmetric and ...asymmetric general-form wave fronts. It seems that, in this model, a complete generalized form of the classical jet formation theory has been developed. Available models that describe the symmetric jet and slug formation phenomenon are very good in such conditions. But the liner and confinement asymmetries, detonation wave front asymmetries, and other specifications, such as manufacturing tolerances, can affect the collapse and the behavior of the jet and slug. Some proposed models that describe asymmetric cases are not closed-form models or are only applicable for limited conditions, such as small asymmetries and a planar wave front. With the presented model, effects of concave, plane, and convex wave fronts on the off-axis velocity of the jet, other parameters of the jet and slug, and effects of an asymmetric wave front on jet formation for a completely symmetric liner and confinement geometry can be evaluated.
This paper presents a closed-form model for the analysis of symmetric planar W-type shaped charges (WSCs) with two V-sections, which produce two primary cores and two primary jets. If these two ...V-sections have proper asymmetry, these primary cores will force two primary jets into a secondary core formed on the axis of symmetry of a planar symmetric WSC. For the analysis of such a planar WSC, a complete generalized model for an asymmetric planar V-shaped charge (VSC) with any desired order of asymmetry is mandatory. In this paper, the model is applied to describe the secondary jet formation in the WSC. By presenting a closed-form analysis of the WSC, the secondary jet specifications can be easily evaluated and, thus, can be compared with respect to the jet quantities in symmetric or asymmetric VSCs. Finally, for the primary and secondary jets, the coherency conditions are investigated, and the critical parameters responsible for these conditions are determined.
This paper presents one and multi-objective crashworthiness optimization of the tapered thin-walled square tube with indentations. In this study, effects of cross section, thickness, taper angle, ...number and radius of indentations (as design variables) on the beam's energy absorption capability during crashes are investigated. The crashworthiness of models is evaluated using two metrics: The specific energy absorption per unit mass (SEA) and the ratio between the average and maximum crushing forces (CFE=Favg/Fmax). The optimum values of the number and radius of the indentations, the taper angle, the tube thickness and the cross section using a combination of response surface (RS) model, genetic algorithm and desirability function optimization are obtained. Multi-objective optimization of the tubes is performed by maximizing a composite objective including CFE and SEA. Analyses involved in this paper are undertaken using finite element models and solver (Abaqus). Also the computer program MATLAB is used to perform all the analyses and the optimization. Multi-objective optimization of the tubes showed that the tapered thin-walled square tubes with indentations have significantly, better crush performance in comparison to those without indentations. It is found that maximum CFE requires large number and radius of indentations, thickness, and cross section with small taper angle, while maximum SEA requires medium number of indentations and radius, large thickness and small taper angle and cross section. Also, the sensitivity of the design variables on the tapered square beam's crash behavior performance is analyzed. The objective functions, including SEA and CFE, were formulated using the Response Surface Method.
•For a tapered thin-walled square tube with indentations, derived model using RSM method for CFE and SEA is relatively accurate.•Using taper geometry cause to structure could withstand against oblique impact loading as well as axial impact.•Adding indentation is an efficient approach to improve tube behavior against axial and oblique impact and its effect on CFE is significant.•The combination of tapered geometry with indentation is an efficient way to obtain a structure with high ability of energy absorption and low peak load.
Circular structures are used in a wide variety of engineering mechanisms and devices. In this paper, an effective algorithm on the basis of complex mappings is proposed to identify defects in ...circular structures using Cartesian damage detection techniques. The efficacy of the proposed algorithm is demonstrated through damage identification in circular plates using Cartesian wavelet analysis. The vibration and thermal responses of the structure, as two important structural signals, are imported into the proposed algorithm to evaluate the abilities of the signals to identify the damage location and severity. Finally, two experimental tests are conducted to explore the efficacy of the proposed algorithm in real applications.
Metastasis is the main cause of death in breast cancer patients. Inflammatory processes following crosstalk between tumor cells and tumor microenvironment play an important role in progression and ...metastasis of cancer. Hence, targeting of these interactions may represent a novel promising strategy for breast cancer therapy. So, we investigated the effects of β‐D mannuronic acid (BDM), a new antiinflammatory agent, on 4T1 breast cancer cell line both in vitro and in vivo. Proliferation assays revealed low‐cytotoxic effect of BDM on 4T1 cells. However, BDM reduced activity of MMP‐2, MMP‐9 and significantly decreased the adhesion of 4T1 cells to extracellular matrix (ECM) in a dose‐dependent manner. The in vivo results demonstrated that BDM strongly inhibits tumor growth and increases lifespan as compared with control mice. The decrease in tumor mass was associated with decreased metastasis, recruitment, and frequency of inflammatory cells in tumor tissue. Our preclinical findings demonstrated that BDM therapy not only prevents formation of chronic inflammatory response but also inhibits crosstalk between tumor cells and their microenvironment, which is associated with reduction of tumor growth and metastasis arrest. Our data imply the use of BDM therapy in future clinical trials to open a new horizon for breast cancer therapy.
Inflammatory processes following crosstalk between tumor cells and tumor microenvironment play an important role in progression and metastasis of cancer. Hence, targeting of these interactions may represent a novel promising strategy for breast cancer therapy.
Cancer-related inflammation (CRI) is associated with the malignant progression of several cancer types. Targeting these pathways is a novel promising strategy for cancer prevention and treatment. In ...this present study, we evaluated the efficacy of α-l-guluronic acid (ALG), a potent anti-inflammatory agent on breast cancer-related inflammation both in vitro and in vivo conditions. Our results indicated that ALG can effectively inhibit the CRI and tumor-promoting mediators (COX-2, MMP2, MMP9, VEGF and proinflammatory cytokines) without direct toxic effects on the cells. Moreover, it was found that, ALG can effectively inhibit the tumor cell adhesion to extracellular matrix, seeding in implantation tissue, reduce accumulation of immunosuppressive and inflammatory cells in tumor-bearing mice. These findings were associated with decreased tumor growth, metastasis, angiogenesis and prolonged mice survival. In conclusion, our data provide a cellular and molecular justification for the use of nonsteroidal anti-inflammatory drugs (NSAIDs) in treating cancer and imply the potential anti-tumor activity of ALG therapy via inhibition of CRI. These findings could lead to the establishment of novel NSAID-based cancer therapy in the near future and open a new horizon for cancer treatment.
PDF
