Contiguous clock lines for pipelined nanomagnet logic

In this paper we study pipelined nanomagnet logic by simulating and comparing varying adjacent clock line structures. Unlike previous simulations, a realistic clock line shape is used in simulations to obtain a more accurate idea of whether or not these clock lines function properly. First, we simulate individual clock lines using Ansys Maxwell 2D according to the parameters of the fabricated clock lines. Then, these clock lines are placed adjacent to one another to simulate how data can propagate from one clock zone to another. Adjusting the clock line layer structure minimizes a dip in the magnetic field at the clock zone boundaries from 35% minimum below the clocking field to a 16% dip. These magnetic field profiles are then used in the object-oriented micromagnetic framework (OOMMF) to simulate lines of nanomagnets. By reducing the gap between contiguous clock lines, we show error free data propagation in the form of a ferromagnetically coupled line of nanomagnets.     

Influence of processing on fracture toughness of Si3N4 + graphene platelet composites

Silicon nitride + 1 wt% graphene platelet composites were prepared using various graphene platelets (GPL) and two processing routes; hot isostatic pressing (HIP) and gas pressure sintering (GPS). The influence of the processing route and graphene platelets’ addition on the fracture toughness has been investigated. The matrix of the composites prepared by GPS consists of Si₃N₄ grains with smaller diameter in comparison to the composites prepared by HIP. The indentation fracture toughness of the composites was in the range 6.1–9.9 MPa m^0.5, which is significantly higher compared to the monolithic silicon nitride 6.5 and 6.3 MPa m^0.5. The highest value of K_IC was 9.9 MPa m^0.5 in the case of composite reinforced by the smallest multilayer graphene nanosheets, prepared by HIP. The composites prepared by GPS exhibit lower fracture toughness, from 6.1 to 8.5 MPa m^0.5. The toughening mechanisms were similar in all composites in the form of crack deflection, crack branching and crack bridging.     

Laser guiding for GeV laser-plasma accelerators

Guiding of relativistically intense laser beams in preformed plasma channels is discussed for development of GeV-class laser accelerators. Experiments using a channel guided laser wakefield accelerator at Lawrence Berkeley National Laboratory (LBNL) have demonstrated that near mono-energetic 100 MeV-class electron beams can be produced with a 10 TW laser system. Analysis, aided by particle-in-cell simulations, as well as experiments with various plasma lengths and densities, indicate that tailoring the length of the accelerator, together with loading of the accelerating structure with beam, is the key to production of mono-energetic electron beams. Increasing the energy towards a GeV and beyond will require reducing the plasma density and design criteria are discussed for an optimized accelerator module. The current progress and future directions are summarized through comparison with conventional accelerators, highlighting the unique short-term prospects for intense radiation sources based on laser-driven plasma accelerators.     

Selective enrichment of low-abundance peptides in complex mixtures by elution-modified displacement chromatography and their identification by electrospray ionization mass spectrometry

Trace components were selectively enriched and detected in the tryptic digest of recombinant human growth hormone using elution-modified displacement chromatography, a hybrid technique combining features of elution and displacement chromatography. Based on the retention behavior of sample components in the elution mode, rapid and selective trace enrichment and high-resolution separation was achieved in a single step by utilizing appropriate combinations of an eluent such as aqueous acetonitrile with the displacer. Mass spectral and chromatographic analysis of displacement zones revealed up to 400-fold enhancement of the concentration of some low-abundance sample components. Potential application of this technique in proteomics to augment the sensitivity of LC-MS and 2-D gel electrophoretic approaches for the detection of biologically important low-abundance species is discussed.     

Improved lower bounds for semi-online bin packing problems

In the paper we deal with lower bounds constructed for the asymptotic competitive ratio of semi-online bin packing and batched bin packing algorithms.We determine the bounds as the solutions of a related nonlinear optimization problem using theoretical analysis and a reliable numerical global optimization method. Our results improve the lower bounds given in Gutin et al. (Discrete Optim 2:71–82, 2005) for some special cases of the batched bin packing problem.     

Module-Based Reinforcement Learning: Experiments with a Real Robot

The behavior of reinforcement learning (RL) algorithms is best understood in completely observable, discrete-time controlled Markov chains with finite state and action spaces. In contrast, robot-learning domains are inherently continuous both in time and space, and moreover are partially observable. Here we suggest a systematic approach to solve such problems in which the available qualitative and quantitative knowledge is used to reduce the complexity of learning task. The steps of the design process are to: (i) decompose the task into subtasks using the qualitative knowledge at hand; (ii) design local controllers to solve the subtasks using the available quantitative knowledge, and (iii) learn a coordination of these controllers by means of reinforcement learning. It is argued that the approach enables fast, semi-automatic, but still high quality robot-control as no fine-tuning of the local controllers is needed. The approach was verified on a non-trivial real-life robot task. Several RL algorithms were compared by ANOVA and it was found that the model-based approach worked significantly better than the model-free approach. The learnt switching strategy performed comparably to a handcrafted version. Moreover, the learnt strategy seemed to exploit certain properties of the environment which were not foreseen in advance, thus supporting the view that adaptive algorithms are advantageous to nonadaptive ones in complex environments.     

New Pilot Plant Studies at the Budapest Waterworks

The quality of water provided by the Budapest Waterworks should comply with the standards prescribed by the European Community. According to these provisions, on one of the major water-producing regions (Csepel Island), rows of wells of 60,000 m³/day yield have been closed recently, and in the immediate future further plants would have been closed because of the high iron and manganese content of the water.

The raw water obtained from 100 different wells will be purified by a water treatment plant of 150,000 m³/day capacity. Considering the high iron content (0.05–0.15 mg/L) and manganese content (0.05–0.2 mg/L), the raw water fails to comply with the requirements of the potable water standard.

Since 1990, over a period of three years, we conducted water purification experiments in several stages. In these, three methods of oxidizing as well as single and double layer open rapid filters were applied to oxidize the manganese (and, to a lesser extent, the water) present in dissolved form, resp., to destroy various living organisms.

In the course of the experiments, it became clear that the chlorine and chlorine + air methods are efficient in case of a small quantity of iron to be oxidized and only 20–25% of the dissolved manganese content could be oxidized.

Neither of the two methods could ensure firm management of microbiological and bacteriological characteristics. The best results were obtained by ozone oxidation, in which case the chemical oxidizing process was almost fully completed and even the chlorine-resistant living organisms could be destroyed.

On the basis of the experiments carried out, the investment program of the water treatment plant was worked out and the conditions of an international tender were compiled whose winner will be commissioned to build up the water works in the time period 1993–1996. One of the main steps of the proposed technology is the ozone treatment.     

The creation of a novel fluorescent protein by guided consensus engineering

Consensus engineering has been used to increase the stability of a number of different proteins, either by creating consensus proteins from scratch or by modifying existing proteins so that their sequences more closely match a consensus sequence. In this paper we describe the first application of consensus engineering to the ab initio creation of a novel fluorescent protein. This was based on the alignment of 31 fluorescent proteins with >62% homology to monomeric Azami green (mAG) protein, and used the sequence of mAG to guide amino acid selection at positions of ambiguity. This consensus green protein is extremely well expressed, monomeric and fluorescent with red shifted absorption and emission characteristics compared to mAG. Although slightly less stable than mAG, it is better expressed and brighter under the excitation conditions typically used in single molecule fluorescence spectroscopy or confocal microscopy. This study illustrates the power of consensus engineering to create stable proteins using the subtle information embedded in the alignment of similar proteins and shows that the benefits of this approach may extend beyond stability.