Hyperspectral pan-sharpening: a variational convex constrained formulation to impose parallel level lines, solved with ADMM

In this paper, we address the issue of hyperspectral pan-sharpening, which consists in fusing a (low spatial resolution) hyperspectral image HX and a (high spatial resolution) panchromatic image P to obtain a high spatial resolution hyperspectral image. The problem is addressed under a variational convex constrained formulation. The objective favors high resolution spectral bands with level lines parallel to those of the panchromatic image. This term is balanced with a total variation term as regularizer. Fit-to-P data and fit-to-HX data constraints are effectively considered as mathematical constraints, which depend on the statistics of the data noise measurements. The developed Alternating Direction Method of Multipliers (ADMM) optimization scheme enables us to solve this problem efficiently despite the non differentiabilities and the huge number of unknowns.Comment: 4 pages, detailed version of proceedings of conference IEEE WHISPERS 201

MHD simulations of three-dimensional Resistive Reconnection in a cylindrical plasma column

Magnetic reconnection is a plasma phenomenon where a topological rearrangement of magnetic field lines with opposite polarity results in dissipation of magnetic energy into heat, kinetic energy and particle acceleration. Such a phenomenon is considered as an efficient mechanism for energy release in laboratory and astrophysical plasmas. An important question is how to make the process fast enough to account for observed explosive energy releases. The classical model for steady state magnetic reconnection predicts reconnection times scaling as $S^{1/2}$ (where $S$ is the Lundquist number) and yields times scales several order of magnitude larger than the observed ones. Earlier two-dimensional MHD simulations showed that for large Lundquist number the reconnection time becomes independent of $S$ ("fast reconnection" regime) due to the presence of the secondary tearing instability that takes place for $S \gtrsim 1 \times 10^4$. We report on our 3D MHD simulations of magnetic reconnection in a magnetically confined cylindrical plasma column under either a pressure balanced or a force-free equilibrium and compare the results with 2D simulations of a circular current sheet. We find that the 3D instabilities acting on these configurations result in a fragmentation of the initial current sheet in small filaments, leading to enhanced dissipation rate that becomes independent of the Lundquist number already at $S \simeq 1\times 10^3$.Comment: 11 pages, 11 figures, accepted for publication in MNRA

Simulation of a balanced low-voltage electrical grid using a simplified network model

A simulation method for low-voltage balanced distribution networks is proposed in this article. The novel method of node powers is based on the general calculation technique of node voltages. By researching only balanced networks, single-phase equivalents of the three-phase system are applicable. For the description of power lines, various parameters and matrices are available. In this work a simplified model is applied by using a purely resistive one. The active power results are solved through an iterative process. A main accomplishment is that the number of iterations needed is independent of the size of the network, and the process rapidly converges. Validation of the method is performed on the IEEE European Low-Voltage Test Feeder network. The simulation results confirm the achievements described in this paper

Unbalanced Workload Allocation in Large Assembly Lines.

In modern production systems that perform under high cost environments, even small improvements in line efficiency represents large savings over the lifetime of an assembly line. In the beginning of modern production systems, it was thought that a `perfectly balanced\u27 line was the most efficient way to design the line. However in practice, the ideal perfectly balanced line seldom occurs, because some degree of imbalance is inevitable. Recent studies have found that unbalanced lines with a bowl shape workload configuration can yield performance in throughput as good as, or even better than those of a perfectly balanced line. This thesis studied the bowl phenomenon in large unpaced assembly lines under stochastic processing times. The control variables analyzed in this study were line length, buffer capacity, task time variability, and percentage of imbalance. A full factorial experiment was designed in order to characterize the main and interaction effects, and computational simulation was used to replicate the behavior of the unbalanced assembly lines. The results of the experiment suggest that unbalancing a large assembly line in a bowl shape workload configuration could provide statistical significant improvements in throughput. Moreover, the results also suggest that the Work in Process (WIP) and the Cycle Time (CT) increase linearly as the Throughput (TR) of the line increases. Even though, the rate at which the TR increases is greater than the rate at which the WIP and CT increases, line designers and production managers need to make an important managerial decision on how much they are willing to increase the WIP and CT of their lines in order to improve the throughput when implementing a bowl shape workload configuration. Furthermore, the results suggested that as the buffer capacity and the number of workstations in the line decreases, and the coefficient of variation of the workstations increases the benefits the bowl phenomenon and the percentage of imbalance of the best bowl configuration increases. In this research, the relationship between the production rate of large assembly lines with a bowl shape workload configuration and its line length, buffer capacity, task time variability, and percentage of imbalance has been studied for the first time. The results would provide valuable guidelines for line designers and managers that want to improve their assembly lines

Balancing of mixed-model parallel U-shaped assembly lines considering model sequences

This is the author accepted manuscript. The final version is available from Taylor & Francis via the DOI in this record.As a consequence of increasing interests in customised products, mixed-model lines have become the most significant components of today’s manufacturing systems to meet surging consumer demand. Also, U-shaped assembly lines have been shown as the intelligent way of producing homogeneous products in large quantities by reducing the workforce need thanks to the crossover workstations. As an innovative idea, we address the mixed-model parallel U-shaped assembly line design which combines the flexibility of mixed-model lines with the efficiency of U-shaped lines and parallel lines. The multi-line stations utilised in between two adjacent lines provide extra efficiency with the opportunity of assigning tasks into workstations in different combinations. The new line configuration is defined and characterised in details and its advantages are explained. A heuristic solution approach is proposed for solving the problem. The proposed approach considers the model sequences on the lines and seeks efficient balancing solutions for their different combinations. An explanatory example is also provided to show the sophisticated structure of the studied problem and explain the running mechanism of the proposed approach. The results of the experimental tests and their statistical analysis indicated that the proposed line design requires fewer number of workstations in comparison with independently balanced mixed-model U-lines

Synchronous Optical Fiber Code-Division Multiple-Access Networks with Bipolar Capacity

A non-coherent synchronous optical fiber code-division multiple-access (CDMA) network is proposed. In this network, sequence-inversion keying (SIK) of intensity modulated unipolar balanced Walsh code sequences is employed, whereby a code sequence is transmitted for each data ‘1’ bit while the logical complement of that sequence is transmitted for each data ‘0’ bit. At the receiver the received optical signal is correlated with the bipolar form of the reference sequence. Since the code sequences are balanced and the unipolar-bipolar correlation is implemented the same correlation functions as a bipolar system can be obtained. Hence, in the proposed synchronous optical fiber CDMA network , the cross-correlation of the address sequence and the undesired sequences is zero, that is, the interference is completely eliminated. Therefore, a very large number of users can transmit at the same time and very high throughput can be achieved. The novel design of programmable transmitter and receiver for non-coherent synchronous optical fiber CDMA networks using balanced Walsh codes is also presented. The transmitter and receiver are designed based on the use of electro-optical switches and optical delay-lines

Maintaining product quality from early to late stage process development

Maintaining product quality of a monoclonal antibody through all phases of clinical development creates many challenges. Changes in cell line, cell line host, media and process conditions can all affect product quality attributes as a product moves from early to late development. All of these factors must be balanced with the desire to maintain protein production levels. Product quality attributes can be impacted by a number of these factors. A case study will be presented on the efforts to maintain product quality when switching cell lines from early to late stage. The effects of media composition and process conditions on product quality attributes will be examined