8,999 research outputs found
Identifying parameters of a broaching design using non-linear optimisation
Broaching is one of the most recognised machining processes that can yield high productivity and high quality when applied properly. One big disadvantage of broaching is that all process parameters, except cutting speed, are built into the broaching tools. Therefore, it is not possible to modify the cutting conditions during the process once the tool is manufactured. Optimal design of broaching tools has a significant impact to increase the productivity and to obtain high quality products. In this paper, an optimisation model for broaching design is presented. The model results in a non-linear non-convex optimisation problem. Analysis of the model structure indicates that the model can be decomposed into smaller problems. The model is applied to a turbine disc broaching problem which is considered as one of the most complex broaching operations
Microwave-induced nonequilibrium temperature in a suspended carbon nanotube
Antenna-coupled suspended single carbon nanotubes exposed to 108 GHz
microwave radiation are shown to be selectively heated with respect to their
metal contacts. This leads to an increase in the conductance as well as to the
development of a power-dependent DC voltage. The increased conductance stems
from the temperature dependence of tunneling into a one-dimensional electron
system. The DC voltage is interpreted as a thermovoltage, due to the increased
temperature of the electron liquid compared to the equilibrium temperature in
the leads
A Modular, Real-Time Fieldbus Architecture for Mobile Robotic Platforms
Cataloged from PDF version of article.The design and construction of complex and reconfigurable embedded systems such as small autonomous mobile robots is a challenging task that involves the selection, interfacing, and programming of a large number of sensors and actuators. Facilitating this tedious process requires modularity and extensibility both in hardware and software components. In this paper, we introduce the universal robot bus (URB), a real-time fieldbus architecture that facilitates rapid integration of heterogeneous sensor and actuator nodes to a central processing unit (CPU) while providing a software abstraction that eliminates complications arising from the lack of hardware homogeneity. Motivated by our primary application area of mobile robotics, URB is designed to be very lightweight and efficient, with real-time support for Recommended Standard (RS) 232 or universal serial bus connections to a central computer and inter-integrated circuit (I(2)C), controller area network, or RS485 bus connections to embedded nodes. It supports automatic synchronization of data acquisition across multiple nodes, provides high data bandwidth at low deterministic latencies, and includes flexible libraries for modular software development both for local nodes and the CPU. This paper describes the design of the URB architecture, provides a careful experimental characterization of its performance, and demonstrates its utility in the context of its deployment in a legged robot platform
Effects of different cavity‑disinfectants and potassium titanyl phosphate laser on microtensile bond strength to primary dentin
Aim: The aim of this in vitro study was to compare the effects of different cavity‑disinfectants and potassium titanyl phosphate (KTP) laser on microtensile bond strength to primary dentin. Chlorhexidine (CHX), propolis (PRO), ozonated water (OW), gaseous ozone (OG) and KTP laser were used for this purpose.Methodology: Twelve primary molar teeth were used in this study. One‑third of the teeth (from coronal portion) were removed to obtain flat surfaces. After applying the cavity‑disinfectants, an adhesive (prime and bond NT) was applied to dentin surfaces, and composite crowns were built up. One group received no pretreatment and was set as a control (CONT). Ten sticks were obtained from these samples and were stressed in tension until failure using a universal testing machine and the data were recorded.Results: The mean strength values (in MPa) of the sticks were OW (11.12) > KTP (9.58) > CHX (7.58) > PRO (7.42) > CONT (6.38) > OG (5.84) and OW showed significantly higher results than the other groups, except KTP group (P < 0.05).Conclusions: OW and KTP might be used safely without compromising the bond strength of restorative materials.Key words: Chlorhexidine gluconate, potassium titanyl phosphate lasers, microtensile bond strength, ozone, primary dentine, propoli
A novel MEFV gene mutation (A511V) in a Chilean FMF patient
Familial Mediterranean fever (FMF) is an autosomal recessive disease which is characterized by recurrent fever and inflammation of serous membranes. A Chilean FMF patient was investigated for MEFV mutations. After DNA extraction, exons 3, 5, 10 and 30UTR region of MEFV gene were analyzed by DNA sequencing while E148Q and R202Q mutations of exon 2 weredetected by RFLP. A novel missense mutation, A511V (c.1532C>T, p.Ala511Val), was found in a heterozygous state in exon 5 of MEFV gene. Also, R202Q (c.605G>A, p.Arg202Gln) was detected in heterozygous state. R202Q was of clinical value in the diagnosis of FMF when combined with adisease causing mutation. In this patient, A511V was detected in compound heterozygous state with R202Q and this association may play an important role in FMF
Simulation studies of spectral subtraction based temperature compensation of FBG sensor for structural health monitoring based on principal component analysis
Nanofiber-enhanced lightweight composite textiles for acoustic applications
This paper proposes lightweight textile acoustic structure, wherein electrospun polyacrylonitrile-based nanofibers enhance sound absorption properties with no weight and thickness penalty. Polyacrylonitrile nanofibers with diameter of 110 ± 7 nm were electrospun on spacer-knitted fabrics by varying deposition amount and surface coating arrangement. Proposed novel approach eliminated additional processing steps such as handling and post-lamination and provided easy scalability of nanofibers at macro-scale. The results showed that the sound absorption of nano-enhanced specimens was improved drastically when deposited amount of nanofibers or its effective surface area increased. Sound propagation paths in different configurations were interpreted from sound absorption and air permeability measurements. The sound absorption coefficient values up to 0.7 are achieved in the low and medium frequency ranges with no weight and thickness penalty by tuning deposition amount and surface coating arrangement
Broadband, Stable, and Non-Iterative Dielectric Constant Measurement of Low-Loss Dielectric Slabs Using a Frequency-Domain Free-Space Method
A broadband, stable, and non-iterative free-space method is proposed for dielectric constant ε′r determination of low-loss dielectric slabs from reflection-only measurements through simple calibration standards (reflect and air). It is applicable for dispersive samples and does not require thickness information. Simulations of non-disperive and dispersive samples are performed to validate our method. Dielectric constant measurements of polyethylene and Polyoxymethylene samples (9–11 GHz) are carried out to examine the accuracy of our method. IEE
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