Fibre laser cutting of carbon fibre reinforced polymeric composites

Owing to the increasing industrial demand for carbon fibre–reinforced polymer composite materials, the interest in effective machining technology grows. The current carbon fibre–reinforced polymer machining technique is dominated by mechanical milling, which often results in high tooling cost and some defects in the machined materials. The exploration of alternative machining techniques is becoming more important. Laser machining as an advanced non-contact technique can potentially improve the machining of carbon fibre–reinforced polymers. However, thermal damages to the machined materials owing to the inhomogeneous, anisotropic and heterogeneous features of these materials have been prohibiting the application of laser machining in industrial scale for carbon fibre–reinforced polymers. In this article, an investigation on the basic characteristics of high-power single-mode ytterbium-doped fibre laser machining of carbon fibre–reinforced polymer is reported. Statistical analysis was performed for the optimisation of the process parameters in single-pass cutting. Furthermore, quality improvement was achieved by the use of multiple-pass cutting technique, which was found to be effective to minimise delamination at low power level and high scanning speeds. </jats:p

Design and construction of a new ultraviolet sensor using CsI deposition in the ionization chamber

In this article, a UV sensor that is an appropriate tool for fire detection has been designed and constructed. The structure of this UV sensor is an air-filled single-wire detector that is able to operate under normal air condition. A reflective CsI photocathode is installed at the end of the sensor chamber to generate photoelectrons in the ion chamber. An electric current is produced by accelerating photoelectrons to the anode in the electric field. The detector is able to measure the intensity of the incident UV rays whenever the current is sufficiently high. Therefore, the sensitivity coefficient of this sensor is found to be 7.67 × 10−6 V/photons/sec. Keywords: CsI Photocathode, Fire Sensor, Ion Chamber, UV Detecto

Formulation of muon range 0-100 TeV and transmission through lead

7-12Muons can penetrate long distances into matter and are less susceptible to radiate effects as compared to electrons. Over a broad energy range, the dominant energy loss is due to ionization mechanism. This makes the shielding of muons and the knowledge of their range considerably important at high-energy accelerators and in other high energy applications. In the present paper, the muon range R(E) from 0-1 GeV in lead is obtained by using muon range data which were generated by SRIM 2012.03 code. For muon energy versus traveled distance E(X), an analytical formula is extracted by a fitting procedure by the aid of Origin 8.0 and Find Graph softwares. For extracting the values of R(E) in the range 0-100TeV and E(X) for less than 100 TeV using the current method faced a limitation. This limitation is due to maximum SRIM energy input card which is 1GeV, so the SRIM range data are used for less than 1 GeV and the GROOM range data for above 1 GeV. In the present paper, the muon energy is calculated using this technique at energy less than 100 TeV for arbitrary traveled distance

Persian manual therapy method for chronic low-back pain with lumbar radiculopathy; a randomized controlled trial

Background: Manual therapy is a non-surgical approach for management of musculoskeletal symptoms. This study investigated safety and efficacy of a Persian manual therapy method (Fateh technique) for management of chronic low-back pain (LBP) and radiculopathy. Methods: In this controlled trial, 52 eligible patients with chronic LBP and lumbar radiculopathy were randomly assigned into two intervention groups; one received a 16-min soft tissue manipulation for four weekly sessions and did two daily home active exercises. The other group only did the two daily exercises for four weeks. Roland-Morris disability score, Visual Analogue Scale scores of LBP, radiculopathy and paresthesia, and finger-to-floor test result were assessed at the baseline, and in fourth and eighth weeks of trial. Results: Data of 48 participants was analyzed. Distributions of age, sex, and duration of symptoms in two groups were the same. Fateh technique respectively decreased pain, radiculopathy, paresthesia, and disability, by 4.28 95% confidence interval: 3.36�5.19, 3.85 2.67�5.03, 1.32 0.37�2.27, and 4.58 3.23�5.93 units, and increased body flexibility by 35.42 6.91�63.92 millimeters. Compared with home exercise, Fateh technique was associated with greater changes in all outcomes. No adverse event has occurred. Conclusions: Fateh technique is safe and effective for management of LBP and radiculopathy in patients without severe progressive symptoms. © 2020 Elsevier Lt