排序方式: 共有46条查询结果,搜索用时 15 毫秒
1.
I. Lazoglu K. Buyukhatipoglu H. Kratz F. Klocke 《Machining Science and Technology》2013,17(2):157-179
In precision machining, due to the recent developments in cutting tools, machine tool structural rigidity and improved CNC controllers, hard turning is an emerging process as an alternative to some of the grinding processes by providing reductions in costs and cycle-times. In industrial environments, hard turning is established for geometry features of parts with low to medium requirements on part quality. Better understanding of cutting forces, stresses and temperature fields, temperature gradients created during the machining are very critical for achieving highest quality products and high productivity in feasible cycle times. To enlarge the capability profile of the hard turning process, this paper introduces prediction models of mechanical and thermal loads during turning of 51CrV4 with hardness of 68 HRC by a CBN tool. The shear flow stress, shear and friction angles are determined from the orthogonal cutting tests. Cutting force coefficients are determined from orthogonal to oblique transformations. Cutting forces, temperature field for the chip and tool are predicted and compared with experimental measurements. The experimental temperature measurements are conducted by the advanced hardware device FIRE-1 (Fiberoptic Ratio Pyrometer). 相似文献
2.
Isil Oz Haluk Rahmi Topcuoglu Mahmut Kandemir Oguz Tosun 《Journal of Parallel and Distributed Computing》2012
Continuously reducing transistor sizes and aggressive low power operating modes employed by modern architectures tend to increase transient error rates. Concurrently, multicore machines are dominating the architectural spectrum today in various application domains. These two trends require a fresh look at resiliency of multithreaded applications against transient errors from a software perspective. In this paper, we propose and evaluate a new metric called the Thread Vulnerability Factor (TVF). A distinguishing characteristic of TVF is that its calculation for a given thread (which is typically one of the threads of a multithreaded application) does not depend on its code alone, but also on the codes of the threads that share resources and data with that thread. As a result, we decompose TVF of a thread into two complementary parts: local and remote. While the former captures the TVF induced by the code of the target thread, the latter represents the vulnerability impact of the threads that interact with the target thread. We quantify the local and remote TVF values for three architectural components (register file, ALUs, and caches) using a set of ten multithreaded applications from the Parsec and Splash-2 benchmark suites. Our experimental evaluation shows that TVF values tend to increase as the number of cores increases, which means the system becomes more vulnerable as the core count rises. We further discuss how TVF metric can be employed to explore performance–reliability tradeoffs in multicores. Reliability-based analysis of compiler optimizations and redundancy-based fault tolerance are also mentioned as potential usages of our TVF metric. 相似文献
3.
Isil Kecik Buyukhatipoglu Asli Secilmis Gulfem Ergun 《Journal of Adhesion Science and Technology》2016,30(22):2439-2452
Objective: The aim of this in vitro study was to evaluate the effect of surface treatments on the shear bond strength of resin cements to zirconia. Material and methods: Sintered zirconia specimens (n = 192) were divided into four different surface treatment groups: control (no treatment); airborne-particle abrasion; glaze layer and hydrofluoric acid (HF) application, and hot etching solution application. Then, each group was divided into four subgroups (n = 12), and three different resin cements were applied to the zirconia surfaces. The shear bond strength value of each specimen was measured after 5000 thermo cycles. The failure types were examined with a stereomicroscope and the effects of the surface treatments were evaluated with a scanning electron microscope. Results were analyzed using analysis of variance and Tukey’s post hoc tests (α = 0.05). Results: The surface treatment and resin cement type significantly affected the bond strength results (p < 0.05). For all resin cements, the airborne-particle abrasion treatment increased the shear bond strength values (p < 0.05). The glaze layer & HF application increased shear bond strength values for all groups, except the Single Bond Universal-RelyX Unicem Aplicap group (p < 0.05). The surface roughness values of airborne-particle abraded specimens were similar to comparable values for specimens from the control group and the hot etching solution group (p > 0.05). The glaze layer & HF application group produced the highest surface roughness values (p < 0.05). Conclusion: The results of this study recommend using the appropriate combination of surface treatment and adhesive/silane coupling agent to achieve durable zirconia-resin bonding. 相似文献
4.
We propose a novel, sound, and complete Simplex-based algorithm for solving linear inequalities over integers. Our algorithm,
which can be viewed as a semantic generalization of the branch-and-bound technique, systematically discovers and excludes entire subspaces of the solution space containing no integer points. Our
main insight is that by focusing on the defining constraints of a vertex, we can compute a proof of unsatisfiability for the intersection of the defining constraints and use this proof to systematically exclude subspaces of the feasible region
with no integer points. We show experimentally that our technique significantly outperforms the top four competitors in the
QF-LIA category of the SMT-COMP ’08 when solving conjunctions of linear inequalities over integers. 相似文献
5.
Peng Gao Isil Berkun Robert D. Schmidt Matthew F. Luzenski Xu Lu Patricia Bordon Sarac Eldon D. Case Timothy P. Hogan 《Journal of Electronic Materials》2014,43(6):1790-1803
Mg2(Si,Sn) compounds are promising candidate low-cost, lightweight, nontoxic thermoelectric materials made from abundant elements and are suited for power generation applications in the intermediate temperature range of 600 K to 800 K. Knowledge on the transport and mechanical properties of Mg2(Si,Sn) compounds is essential to the design of Mg2(Si,Sn)-based thermoelectric devices. In this work, such materials were synthesized using the molten-salt sealing method and were powder processed, followed by pulsed electric sintering densification. A set of Mg2.08Si0.4?x Sn0.6Sb x (0 ≤ x ≤ 0.072) compounds were investigated, and a peak ZT of 1.50 was obtained at 716 K in Mg2.08Si0.364Sn0.6Sb0.036. The high ZT is attributed to a high electrical conductivity in these samples, possibly caused by a magnesium deficiency in the final product. The mechanical response of the material to stresses is a function of the elastic moduli. The temperature-dependent Young’s modulus, shear modulus, bulk modulus, Poisson’s ratio, acoustic wave speeds, and acoustic Debye temperature of the undoped Mg2(Si,Sn) compounds were measured using resonant ultrasound spectroscopy from 295 K to 603 K. In addition, the hardness and fracture toughness were measured at room temperature. 相似文献
6.
Montmorillonite modified with distearyldimethyl ammonium chloride (C18-QAC) (Nanofil-15) (NF15) was incorporated into polydimethylsiloxane-urea
(silicone-urea, PSU) copolymers. PSU was obtained by the reaction of equimolar amounts of aminopropyl terminated polydimethylsiloxane
(PDMS) oligomer (<Mn> = 3,200 g/mol) and bis(4-isocyanatohexyl)methane (HMDI). A series of PSU/NF15 nanocomposites were prepared by solution blending
with organoclay loadings ranging from 0.80 to 9.60% by weight, corresponding to 0.30 to 3.60% C18-QAC. Colloidal dispersions
of organophilic clay (NF15) in isopropanol were mixed with the PSU solution in isopropanol and were subjected to ultrasonic
treatment. Composite films were obtained by solution casting. FTIR spectroscopy confirmed that the organoclay mainly interacted
with the urea groups but not with PDMS. XRD analysis showed that nanocomposites containing up to 6.40% by weight of organoclay
had fully exfoliated silicate layers in the polymer matrix, whereas 9.60% loading had an intercalated structure. Physicochemical
properties of nanocomposites were determined. PSU/NF15 nanocomposites displayed excellent long-term antibacterial properties
against E. coli. 相似文献
7.
I. Isil Gurten Inal Murat Akdemir Mustafa Kaya 《International Journal of Hydrogen Energy》2021,46(41):21534-21541
In the present study, a Mn-supported catalyst material developed from Microcystis aeruginosa microalgae for hydrogen generation was tested as a supercapacitor electrode material for the first time. The catalyst material (MA-HCl-Mn) was examined for hydrogen generation through methanolysis of NaBH4, and it demonstrated good catalytic activity. Symmetric and asymmetric supercapacitor cells were prepared using MA-HCl-Mn as the electrode material. The electrochemical performance of the cells were evaluated by a two-electrode system using 2 M KOH as the electrolyte. The gravimetric capacitance of the symmetric and asymmetric cells found to be 40 F/g and 71 F/g, respectively. It was concluded that MA-HCl-Mn served as a sustainable, dual functional material showing a high catalytic activity for the hydrogen generation and a promising electrochemical performance as the supercapacitor electrode. 相似文献
8.
Aysun Cireli Nurhan Onar M. Faruk Ebeoglugil Isil Kayatekin Bengi Kutlu Osman Culha Erdal Celik 《应用聚合物科学杂志》2007,105(6):3748-3756
In this study, flame retardancy properties of fabrics treated with phosphorous (P) doped and undoped SiO2 thin films were developed by sol–gel technique. As to this aim, P‐doped and undoped SiO2 film were coated on cotton fabric from the solutions prepared from P, Si‐based precursors, solvent, and chelating agent at low temperature in air using sol–gel technique. To determine solution characteristics, which affect thin film structure, turbidity, pH values, and rheological properties of the prepared solutions were measured using a turbidimeter, a pH meter, and a rheometer machines before coating process. The thermal, structural, and microstructural characterization of the coating were done using differential thermal analysis/thermograviometry, fourier transform infrared spectroscopy, X‐ray diffractometry, and scanning electron microscopy. In addition, tensile strength, wash fastness, flame retandancy, and lightness properties of the coated fabrics were determined. To compensate the slight loss of tensile strength of samples, which occurred at the treated fabrics with P‐doped Si‐based solutions, the cotton fabrics were coated with polyurethane films during second step. In conclusion, the flame retardant cotton fabric with durability of washing as halogen‐free without requiring after treatment with formaldehyde was fabricated using sol–gel processing for the first time. Moreover the cotton fabrics, which were treated with P‐doped Si‐based solutions and then coated with polyurethane at second step, still has got nonflammable property. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 相似文献
9.
Optimization of dry powder deposition parameters for production of large substrates using functionally graded ceramics 下载免费PDF全文
Isil Berkun Gullu Kiziltas 《International Journal of Applied Ceramic Technology》2018,15(5):1199-1211
The ability to control the spatial variation in three dimensions of dielectric properties is known to play a crucial role in achieving novel electromagnetic performance such as miniaturization and high gain of broadband antennas. To address this need, the objective in this paper is to use earlier proposed Dry Powder Deposition to produce large substrates of Functionally Graded Materials with spatially controlled CaTiO3‐MgTiO3‐Mg2TiO4 dielectrics. We present an in‐depth analysis and optimization of critical processing parameters such as compaction pressure, sintering temperature, and dwell time. Using the optimized compaction and co‐sintering process, spatially varying large (8.2 cm × 8.2 cm) substrates were produced without the presence of any significant cracks and warping. In addition to these structural functionalities, sintered ceramic constituents of the designed substrate display targeted dielectric permittivity values of a miniaturized broadband Satellite Communication Ultra High Frequency antenna at the optimized conditions. This optimized route opens up possibilities for multifunctional metrics to be addressed for other applications calling for different spatial distributions of large Functionally Graded Materials possibly with the same family of ceramic constituents. 相似文献