Two Neural Network Construction Methods

Two low complexity methods for neural network construction, that are applicable to various neural network models, are introduced and evaluated for high order perceptrons. The methods are based on a Boolean approximation of real-valued data. This approximation is used to construct an initial neural network topology which is subsequently trained on the original (real-valued) data. The methods are evaluated for their effectiveness in reducing the network size and increasing the network's generalization capabilities in comparison to fully connected high order perceptrons.     

A Graph Representation Scheme for Process Planning of Machined Parts

A new generic graph representation scheme for process planning is presented. It has been specifically developed to facilitate the planning and control of geometric dimensions and tolerances. Relationships between cut, location, and datum surfaces and machining operations are represented by a graph consisting of connected boxes. A box is a multi-terminal node that corresponds to a machine set-up. Machining operations are depicted as arrows inside the box. These connect input nodes, representing datum and location surfaces, to output nodes, representing machined surfaces. External connectors join boxes together to form a directed graph. The main purpose of these connectors is to indicate the surfaces (from prior set-ups) that are used as location and datum surfaces for later set-ups. The representation covers cutting operations and non-cutting operations, such as surface finishes and coatings. The paper concludes with an example that illustrates the application and power of the scheme.     

Power assignment problems in wireless communication: Covering points by disks,reaching few receivers quickly,and energy-efficient travelling salesman tours

In this paper, we present approximation algorithms for a variety of problems occurring in the design of energy-efficient wireless communication networks. We first study the k-station network problem, where for a set S of stations and some constant k, one wants to assign transmission powers to at most k senders such that every station in S can receive a signal from at least one sender. We give a (1 + ?)-approximation algorithm for this problem. The second problem deals with energy-efficient networks, allowing bounded hop multicast operations, that is given a subset C of the stations S and a designated source node s ∈ S, we want to assign powers to the sending stations, such that every node in C can be reached by a transmission from s within k hops. For this problem, we provide an algorithm which runs in time linear in ∣S∣. The last problem deals with a variant of the non-metric TSP problem where the edge costs correspond to the Euclidean distances to the power of some α ? 1; this problem is motivated by data aggregation schemes in wireless sensor networks. We provide a simple constant approximation algorithm, which improves upon previous results when 2 ? α ? 2.7.     

Degradation of polymethylmethacrylate by synchrotron radiation

Summary Polymethylmethacrylate was irradiated with X-rays at absorbed dose rates between 3.8 × 10³ and 7.1 × 10⁵ J.g^–1. h^–1. The 100 eV-yield for main-chain scission was determined as G(S)_X-ray= 0.33. It is independent of the absorbed dose rate. The difference between G(S)_X-ray and G(S)_-ray(G(S)_-ray= 1.5 ± 0.2) is attributed to a true linear energy transfer (LET) effect.     

Consistent DNA Hypomethylations in Prostate Cancer

With approximately 1.4 million men annually diagnosed with prostate cancer (PCa) worldwide, PCa remains a dreaded threat to life and source of devastating morbidity. In recent decades, a significant decrease in age-specific PCa mortality has been achieved by increasing prostate-specific antigen (PSA) screening and improving treatments. Nevertheless, upcoming, augmented recommendations against PSA screening underline an escalating disproportion between the benefit and harm of current diagnosis/prognosis and application of radical treatment standards. Undoubtedly, new potent diagnostic and prognostic tools are urgently needed to alleviate this tensed situation. They should allow a more reliable early assessment of the upcoming threat, in order to enable applying timely adjusted and personalized therapy and monitoring. Here, we present a basic study on an epigenetic screening approach by Methylated DNA Immunoprecipitation (MeDIP). We identified genes associated with hypomethylated CpG islands in three PCa sample cohorts. By adjusting our computational biology analyses to focus on single CpG-enriched 60-nucleotide-long DNA probes, we revealed numerous consistently differential methylated DNA segments in PCa. They were associated among other genes with NOTCH3, CDK2AP1, KLK4, and ADAM15. These can be used for early discrimination, and might contribute to a new epigenetic tumor classification system of PCa. Our analysis shows that we can dissect short, differential methylated CpG-rich DNA fragments and combinations of them that are consistently present in all tumors. We name them tumor cell-specific differential methylated CpG dinucleotide signatures (TUMS).     

Co-generation of Ammonia and H2 from H2O Vapor and N2 Using a Membrane Electrode Assembly

The direct electrochemical synthesis of NH₃ from nitrogen and water vapor without the use of a fossil carbon source is highly desired. This synthesis is a viable option to store energy and produce fertilizer precursors. Here, a new Pt-free membrane electrode assembly is presented. An electrochemical membrane reactor demonstrates the feasibility of co-generating NH₃ and H₂ directly from nitrogen and water vapor at ambient conditions. An unprecedented high NH₃-specific current efficiency of up to 27.5% using Ti as cathodic catalyst is reported. The co-generation can be tuned by the balance of process parameters.     

Optimizing conditional value-at-risk in dynamic pricing

OR Spectrum - Many industries use dynamic pricing on an operational level to maximize revenue from selling a fixed capacity over a finite horizon. Classical risk-neutral approaches do not...     

Combined forging and punching of long pieces

Many forged parts include piercings such as bearing surfaces. The forged pieces show a residual volume in the cross sectional area of which needs to be removed in an additional manufacturing step. By integrating this hitherto separately performed operation into the final forging step the process chain can be shortened significantly. However, up to date there is no information available on how the process parameters influence factors like dimensional accuracy, surface quality and fibre orientation in the pierced area when forming and piercing operations are combined. Therefore, a novel combined forging-/piercing- process was designed at the IPH. Trials were performed in a project with different experimental settings of the relevant process parameters like forging temperature, tool and work piece material, punch and work piece geometry. Two test parts were designed. For the first part of the project a rotation symmetric part and for the second part a part with a distinct longitudinal axis. Due to the direct correlation between residual volume thickness to be pierced and interior die pressure which determines the surface quality of the pierced area, the inserted mass is varied in the first part of the project additionally. The results of these investigations showed that the variation of the inserted mass and the forging temperature have a distinct effect on the dimensional and form accuracy of the work pieces. In contrast, the punch and work piece geometry have no effect on the form accuracy of the piercing which is shown in the results of the second project.