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In this work, detailed numerical modeling is performed for front junction (FJ) and rear junction (RJ) n-type Si solar cells with screen-printed double-side poly-Si based tunnel oxide passivated contacts (TOPCon). A roadmap for efficiency projections of commercial-type RJ and FJ topologies reaching ~24% and >22.5% efficiencies, respectively, has been developed to quantify and explain the impact of various technological innovations on the performance of each design. By investigating several key parameters such as front poly sheet resistance and thickness, bulk material properties, and current transport in our simulation model, we determine and explain why RJ cells outperform FJ cells. Our findings reveal that FJ suffers from present technological limitations of p-poly based passivated contacts, namely, i) large recombination observed in textured p-TOPCon layers and ii) low boron solid solubility and hole mobility in p-poly Si which results in very high sheet resistance of the front p-poly emitter that contributes to FF degradation, especially when using thin poly layer to reduce absorption loss. RJ, on the other hand, desensitizes the cell efficiency to front sheet resistance allowing application of ultra-thin front n-poly layers and is therefore ideally suited for double-side TOPCon cells.

We present a new deep network layer called “Dynamic Convolutional Layer” which is a generalization of the convolutional layer. The conventional convolutional layer uses filters that are learned during training and are held constant during testing. In contrast, the dynamic convolutional layer uses filters that will vary from input to input during testing. This is achieved by learning a function that maps the input to the filters. We apply the dynamic convolutional layer to the application of short range weather prediction and show performance improvements compared to other baselines.

In recent years, the problem of associating a sentence with an image has gained a lot of attention. This work continues to push the envelope and makes further progress in the performance of image annotation and image search by a sentence tasks. In this work, we are using the Fisher Vector as a sentence representation by pooling the word2vec embedding of each word in the sentence. The Fisher Vector is typically taken as the gradients of the log-likelihood of descriptors, with respect to the parameters of a Gaussian Mixture Model (GMM). In this work we present two other Mixture Models and derive their Expectation-Maximization and Fisher Vector expressions. The first is a Laplacian Mixture Model (LMM), which is based on the Laplacian distribution. The second Mixture Model presented is a Hybrid Gaussian-Laplacian Mixture Model (HGLMM) which is based on a weighted geometric mean of the Gaussian and Laplacian distribution. Finally, by using the new Fisher Vectors derived from HGLMMs to represent sentences, we achieve state-of-the-art results for both the image annotation and the image search by a sentence tasks on four benchmarks: Pascal1K, Flickr8K, Flickr30K, and COCO.

The number of images and videos available for search on the Internet is in the order of a trillion images, making current brute force search techniques prohibitively inefficient on such large scales. As society continues to increase our desire and ability to search these vast collections of data, improving upon traditional face recognition search techniques becomes an important problem to address. Because face recognition (and other biometric) algorithms are only commercially available as black box systems, any indexing scheme developed to perform efficient search must operate without access to the underlying feature vectors used to measure facial similarity. To address this restriction, we propose a structured search that separates the facial feature space into clusters derived from sets of prototype subjects we refer to as “synecdoches”. After an offline training step, our proposed method assigns each gallery image to a cluster in the face space based on its similarity to a set of synecdoche clusters. In turn, query images are compared to the target gallery images based on the closest synecdoche cluster in sequence. Our results show a minimal drop in accuracy when only considering half of the clusters, thus reducing the search space in half. Additional experiments demonstrate the viability of our proposed approach to improve search efficiency amidst the common restriction of a black box matcher.

Next generation radio telescopes can greatly benefit from reflector antenna feeds that demonstrate very wide frequency bandwidth and can potentially realize low noise performance of the receivers. In this paper, we provide an overview of the current developments at the national radio observatories in Sweden and USA that make use of novel multi-port antenna feeds, such as the Sinuous Antenna and Eleven Antenna. The focus of this overview is on the system performance, when using this technology at high or very low frequencies, i.e. when the feed-receiver system is fully or partially (cryogenically) cooled.

A new Mode Partition Noise model for VCSEL-based optical links capturing RIN and MPN via a covariance matrix is proposed and experimental parameter extraction is performed. The model removes Ogawa-Agrawal model assumptions inappropriate for VCSELs.

We present an overview of the recent developments of a cryogenic 2–14 GHz feed system for the Very Long Baseline Interferometry 2010 (VLBL2010) project. The developments include a new balun feeding network, a new circular Eleven feed, system noise temperature modeling and testing, integration with different low noise amplifiers (LNAs), and cryostat design and integration.

Recently the authors proposed new scintillator designs for the detection of thermal neutrons based on initiating the (n, ±) reaction in 6Li-doped ZnO and ZnO/6LiF/ZnO structures as a potential replacement for 3He tubes [1]. In this paper the critical material properties and structure parameters required to optimize detector performance both for high sensitivity and high neutron-to-gamma ray discrimination are identified and examined. Scintillator neutron detector design guidelines are established through modeling and simulation of detector construction based on experimental results.

The Eleven feed is a compact, low-profile decade-bandwidth log-periodic dual-dipole array antenna. It has many advantages: a constant phase center location, constant beam width over a decade bandwidth, high BOR 1 efficiency, low cross polar level and good reflection coefficient, all over a decade bandwidth. This paper reviews the recent developments on the Eleven feed technology, which covers several important issues for the applications of the feed in decade bandwidth radio telescopes.

Wideband systems forms an integral part of future radio astronomical and geodetic research [1, 2]. Fast comparisons between and of systems capabilities is required for planning and evaluation. This paper presents calculations, and theoretical A/T curves, for cryogenic and ambient system implementations using the Eleven feed and similar band LNAs. The Eleven feed is a decade band antenna and, similar band low noise amplifiers options, developed at Caltech and Chalmers are used for the model. The Chalmer's LNA is designed for use at room temperature, and the Caltech LNA, cryogenic temperatures. The achievable SNR of a radio telescopes is a product of the sensitivity of the receiver and achievable gain. Commonly expressed as a single figure of merit A/T: the ratio of the effective reflector area, A to the total system noise temperature, T. The Eleven antenna was first described in [3], and the further developments are described in [4]. Other candidate feeds are the quadridge horn [5] and the quasi-self-complementary antenna [6].

Radial Shaft Seals (RSS) are widely used in all fields of mechanical engineering for sealing of rotating elements. Up to now there has been no possibility to include Radial Shaft Seals adequately into the lifetime calculation of mechanical systems. In this paper the difficulties in accelerated life testing of RSS are presented and discussed. First of all, this involves the consideration of the RSS only as one part of a complex sealing system. Then, the influences on reliability and lifetime are specified and a definition of a failure itself is given. The main part identifies the major failure modes, the failure causes and the effects of these failures on the sealing system. All those points listed above result in a definition of testing parameters and first accelerated life tests of RSS. Finally an outlook based on the results of the first tests is given.

Because of their excellent crystalline quality, high surface-to-volume ratio, and direct bandgap, GaN nanowires (NWs) grown by molecular beam epitaxy (MBE) are a promising platform for the development of nanoscale devices for a variety of optoelectronic, electronic, sensing, and nanomechanical applications. Understanding and harnessing the field effect behavior of GaN NWs is a crucial step in the evolution of such devices. This paper investigates an alternative approach to GaN FETs by fabricating and testing top-gated metal-semiconductor FETs based on Si-doped GaN NWs grown by catalyst-free MBE. Improvements to the MESFET design and to the analysis of NW FET behavior are proposed.

This paper presents a strategy for the robust design of an optoelectronic communication system consisting of non-linearly tapered waveguide and a photodetector. The inductive design exploration method (IDEM) is implemented to reduce the potential uncertainties existing when simulation models are combined in a design process. This method assists us in looking for robust solutions rather than an optimal solution for this problem. A robust ranged set of design solutions could perform better under uncertainty than optimal single solutions which may deteriorate significantly when uncertainties make conditions or assumptions change. In this paper, the emphasis is on the method.

The simulation method presented above will be applied to various VCSEL design configurations in order to obtain comparative information about the utility of certain design features. We show the three dimensional fundamental mode pattern of a standard oxide confined VCSEL with a l /spl mu/m diameter oxide aperture which occupies the first DBR layer. Design parameters which will be tested include oxide placement, oxide thickness, tapering of the oxide tip, and DBR design, amongst others.

Summary form only given, as follows. The optical properties of oxide-confined vertical cavity surface emitting lasers have recently become a subject of great interest, as the threshold current for such devices has already been pushed to record low values and potentially may drop further. Of interest, then, is an optical simulator which may compare various designs and be useful in determining which oxide configurations are most desirable. We have developed a full-vector cylindrical mode solver based on a novel gain eigenvalue equation. This simulator uses the analytic tensor Green's function of the planar VCSEL cavity to treat scattering loss, diffraction loss, and the open VCSEL boundary with a great deal of accuracy. A relatively small, dense matrix is assembled which describes the interactions between the gain and oxide regions. Once the matrix has been assembled, a wide variety of designs may be quickly analyzed merely by multiplying the matrix by a vector and diagonalizing. The output from the simulator includes the mode field patterns, the gain required to lase, and the lasing frequency for as many modes of the VCSEL as are required. Thus, it is a useful interactive tool for determining the lowest threshold designs, as well as determining which designs are best for single-mode operation. The mode solver is reviewed, and various oxide confined VCSEL designs of current interest are compared and contrasted to suggest likely design improvements.