Determination of the phase of an electromagnetic field via incoherent detection of fluorescence

We show that the phase of a field can be determined by incoherent detection of the population of one state of a two-level system if the Rabi frequency is comparable to the Bohr frequency so that the rotating wave approximation is inappropriate. This implies that a process employing the measurement of population is not a square-law detector in this limit. We discuss how the sensitivity of the degree of excitation to the phase of the field may pose severe constraints on precise rotations of quantum bits involving low-frequency transitions. We present a scheme for observing this effect in an atomic beam, despite the spread in the interaction time.Comment: 4 pages, 2 fig

Throughput and Yield Improvement for a Continuous Discrete-Product Manufacturing System

A seam-welded steel pipe manufacturing process has mainly four distinct major design and/or operational problems dealing with buffer inventory, cutting tools, pipe sizing and inspection-rework facility. The general objective of this research is to optimally solve these four important problems to improve the throughput and yield of the system at a minimum cost. The first problem of this research finds the optimal buffer capacity of steel strip coils to minimize the maintenance and downtime related costs. The total cost function for this coil feeding system is formulated as a constrained non-linear programming (NLP) problem which is solved with a search algorithm. The second problem aims at finding the optimal tool magazine reload timing, magazine size and the order quantity for the cutting tools. This tool magazine system is formulated as a mixed-integer NLP problem which is solved for minimizing the total cost. The third problem deals with different type of manufacturing defects. The profit function of this problem forms a binary integer NLP problem which involves multiple integrals with several exponential and discrete functions. An exhaustive search method is employed to find the optimum strategy for dealing with the defects and pipe sizing. The fourth problem pertains to the number of servers and floor space allocations for the off-line inspection-rework facility. The total cost function forms an integer NLP structure, which is minimized with a customized search algorithm. In order to judge the impact of the above-mentioned problems, an overall equipment effectiveness (OEE) measure, coined as monetary loss based regression (MLBR) method, is also developed as the fifth problem to assess the performance of the entire manufacturing system. Finally, a numerical simulation of the entire process is conducted to illustrate the applications of the optimum parameters setting and to evaluate the overall effectiveness of the simulated system. The successful improvement of the simulated system supports this research to be implemented in a real manufacturing setup. Different pathways shown here for improving the throughput and yield of industrial systems reflect not only to the improvement of methodologies and techniques but also to the advancement of new technology and national economy

Streamer inception and imaging in various atmospheres

Streamers are the first stage of many discharges involving high voltages.They consist of a propagating ionization front leaving behind atrail of conductive, quasi-neutral plasma. In this contribution we willshow experiments on streamers revealing some of their most importantproperties: their inception and their propagation and branchingbehaviour.We study streamer inception by applying repetitive high voltagepulses and studying the statistics of inception delay. By means of smallbias pulses between the high voltage pulses, we are able to manipulatethese statistics, which reveals a lot on the processes governing theinception.Secondly, we study the propagation and branching of streamers bya combination of stereoscopic and stroboscopic measurements of ’lowcomplexity’ streamer discharges. We have developed automated routineswhich can determine propagation velocities, branching angles andmuch more from these and can directly compare these against numericalresults, thereby also giving unprecedented insights into the fundamentalsof such discharges

Soil abrasiveness for EPB-TBM along Tehran metro tunnel line 7, Iran

Full-face shielded tunnel boring machines (TBM) including earth pressure balance (EPB) shields have been used almost exclusively for soft ground tunneling because of the many advantages the offer in comparison to the conventional methods. The total number of EPB-TBMs that were utilized for tunneling between 2005 and 2010 is approximately 350 units worldwide as reported by [1]. These machines encounter a wide range of geological conditions and hazards. One of the most critical adverse conditions is encountering abrasive soils and excessive wear on the cutting tools and the cutterhead as has been reported in many EPB tunneling projects worldwide [2], [3]. Inspection and maintenance of cutting tools below the groundwater table is usually performed under hyperbaric conditions where air pressure is used to provide tunnel face stability. This involves creating a plug at the face, removing the spoils (muck), applying compressed air, and allowing the crew into the cutting chamber via an air lock. This entire process can take days to complete. Consequently, the tool inspection and maintenance in soft ground tunneling is a time consuming, risky, dangerous, and costly [4]. Abrasiveness of soil and rock is a factor with considerable influence on the wear of tools. The wear of excavation tools is an important measurable indicator of rock and soil excavation in tunnelling, in addition to the volume of material excavated (Fig. 1). [5]. In mechanized tunneling the term wear is classified into two categories, primary wear and secondary wear. Primary wear is an expected type of wear that can occur on several parts of the excavation tools, such as drag bits, disc cutters, scrapers and buckets, etc. Secondary wear, on the other hand, is an unplanned type of wear that affects the cutterhead spokes, cutter saddles, bulkheads and also much conveyance parts such as the screw conveyor. The first type of wear requires replacement at appropriate intervals whereas the second type is not and therefore the parts are not anticipated to be replaced regularly. As such the TBM performance may be affected significantly if sever secondary wear occurs [6]. In this paper, an investigation was undertaken to discern the main cause of the observed wear on EPB-TBM of Tehran Metro Line 7 (North-South lot). The wear potential of soils and rocks are assessed with respect to approach on the matter was introduced by [5] and Cerchar test, respectively