Study of Rock-Lining Interaction for Circular Tunnels Using Finite Element Analysis

Finite element technique is used to model two phases of tunneling process, namely; excavation and rocklining interaction. The excavation phase is responsible for determining the pre-lining rock mass deformations and the reduced in-situ stresses. The interaction phase models the compatibility of the rock-lining system. The deformations and stresses of the rock-lining system and the final rock mass pressure acting on the lining are determined. The finite element results are compared with the results of the Convergence-Confinement method for the case study (Shimizu Tunnel) that was guided by field measurements. One of the main objectives of this study is to investigate the effect of different parameters on the behavior of excavated tunnel before and after lining activation. The analysis followed the same procedure which had been applied in the analysis of the case of Shimizu Tunnel taking into consideration the different values of the tunnel radius and the depth of excavated tunnel through different qualities of rock ranging between poor, moderate and hard rock. The parametric study has been conducted for circular tunnel. The first lining system involved in this study was assumed to be shotcrete of thicknesses of 20, 30, 40 and 50cm, and the second lining system was steel ribs with shotcrete of thicknesses of 20, 30, 40 and 50cm. The results of Finite Element Analysis were presented for different thicknesses

Deterministic secure quantum communication with and without entanglement

We present a protocol for sending a message over a quantum channel with different layers of security that will prevent an eavesdropper from deciphering the message without being detected. The protocol has two versions where the bits are encoded in either pairs of entangled photons or separate photons. Unlike many other protocols, it requires a one-way, rather than a two-way, quantum channel and does not require a quantum memor. A quantum key is used to encrypt the message and both the key and the message are sent over the quantum channle with the same quantum encoding technique. The key is sent only if no eavesdropper is detected.Comment: 9 pages, 3 figures. Major changes in section 3 and 4. Accepted for publication in Physica Script

The Potential of Hydrocyclone Application for Mammalian Cell Separation in Perfusion Cultivation Bioreactors

Hydrocyclones have been traditionally applied for long times in many industrial fields, such as in mineral processing and mining, chemical and petrochemical, and food industries. They have many characteristics that favor them as separation system in solid/liquid, gas/liquid and liquid/liquid processes. During the last two decades, they have been evaluated for their possible application in the separation of microbial and mammalian cells. Nowadays, mammalian cells are widely used for the production of a large number of valuable therapeutic proteins, antibodies, hormones and vaccines. This review highlights the potential of the application of hydrocyclones for mammalian cell separation in continuous perfusion biorecators. The discussion will cover the structure of hydrocyclone, mechanism of separation inside hydrocyclones, different theories describing the separation process, as well as the effect of changing different geometrical variables on the efficiency and performance of the separation process. Furthermore, we will focus on the latest developments achieved in the field of separation of living cells in both laboratory and pilot plant cultivation scales

Interpreting Recoil For Undergraduate Students

In this paper, I outline some problems in the students' understanding of the explanation of recoil motion when introduced to them in the context of Newton's third law. I propose to explain the origin of recoil from a microscopic point of view, which emphasizes the exact mechanism leading to recoil. This mechanism differs from one system to another. Several examples that can be easily implemented in the classroom environment are given in this paper. Such a profound understanding of the origin of recoil help students avoid some of the misconceptions that might arise from the phenomenological approach, and stimulates their thinking in the fundamental origins of other physical phenomena.Comment: To Appear in The Physics Teacher Magazin

Influence of Silica Fume, Fly Ash, Super Pozz and High Slag Cement on Water Permeability and Strength of Concrete

In this study, effects of mineral admixtures on water permeability and compressive strength of concretes containing silica fume (SF), fly ash (FA) and super pozz (SP) were experimentally investigated. Permeability of concrete was determined through DIN 1048 (Part 5). The research variables included cement type, ordinary Portland cement (OPC) or high slag cement (HSC), and mineral admixtures content was used as a partial cement replacement. They were incorporated into concrete at the levels of 5%, 10% and 15% for silica fume and 10%, 20% and 30% for fly ash or super pozz by weight of cement. Water-cement ratio of 0.40 was used and tests were carried out at 28 days. From the tests, the lowest measured water permeability values were for the 10% super pozz and 10% silica fume or 20% fly ash mixes. The highest compressive strength of concretes determined was for 10% silica fume mix with ordinary Portland cement and was reduced with the increase in the replacement ratios for other mineral admixtures than ordinary Portland cement concrete. The main objective of this research was to determine the water permeability and compressive strength of concrete containing silica fume, fly ash, super pozz and high slag cement to achieve the best concrete mixture having lowest permeability. The results were compared to those of the control concrete; ordinary Portland cement concrete without admixtures. The optimum cement replacement by FA, SP and SF in this experiment was 10% SP. The knowledge on the strength and permeability of concrete containing silica fume, fly ash, super pozz and high slag cement could be beneficial in the utilization of these waste materials in concrete work, especially on the topic of durability

Non-surgical treatment of massive traumatic corpus callosum hematoma after blunt head injury: A case report

Massive hematoma of the corpus callosum caused by blunt head trauma is an extremely rare lesion. Most frequent traumatic lesions involve the corpus callosum are diffuse axonal injuries. They might be associated with small hemorrhagic foci in the hemispheric and brain stem white matter, intraventricular hemorrhages, subarachnoid hemorrhages, traumatic lesions of the septum pellucidum and fornix. Many cases of corpus callosum injury present with permanent disconnection syndrome. We present a case of a 32-year-old female suffered blunt head trauma resulted in massive corpus callosum hematoma which was managed non-surgically. The patient initially had a reduced conscious level and symptoms of disconnection syndrome, and significant recovery was observed at 6 months follow up

Quantum key distribution based on the quantum eraser

Quantum information and quantum foundations are becoming popular topics for advanced undergraduate courses. Many of the fundamental concepts and applications in these two fields, such as delayed choice experiments and quantum encryption, are comprehensible to undergraduates with basic knowledge of quantum mechanics. In this paper, we show that the quantum eraser, usually used to study the duality between wave and particle properties, can also serve as a generic platform for quantum key distribution. We present a pedagogical example of an algorithm to securely share random keys using the quantum eraser platform and propose its implementation with quantum circuits.Comment: 7 pages, 4 figures; updated versio