Decision Heuristics in a Constraint-based Product Configurator

This paper presents an evaluation of decision heuristics of solvers of the Boolean satisfiability problem (SAT) in the context of constraint-based product configuration. In product configuration, variable assignments are searched in real-time, based on interactively formulated user requirements. Operating on user’s successive input poses new requirements, such as low-latency interactivity as well as deterministic and minimal implicit product changes. This work presents a performance evaluation of several heuristics from the SAT literature along with new variants that address the special real-time requirements of incremental product configuration. Our results show that the execution time on an industrial benchmark can be significantly improved with our new heuristic

Construction of Decision Diagrams for Product Configuration

Knowledge compilation is a well-researched field focused on translating propositional logic formulas into efficient data structures that allow polynomial-time online queries related to the SAT problem. Knowledge compilation techniques can be used to partition product configuration tasks into two distinct phases: fast online processing and slow offline preprocessing. Binary Decision Diagrams (BDDs) are widely studied in this area and provide a graph representation of Boolean formulas. However, BDD construction can be time-consuming, particularly for large instances, as their size grows exponentially with the number of variables. This paper explores methods to improve BDD construction time, including optimizing variable ordering. The evaluation involves applying these techniques to formulas in Rich Conjunctive Normal Form, comparing the results with Sentential Decision Diagrams. The experiments use CAS Software AG benchmarks

Does Selection against Transcriptional Interference Shape Retroelement-Free Regions in Mammalian Genomes?

BACKGROUND: Eukaryotic genomes are scattered with retroelements that proliferate through retrotransposition. Although retroelements make up around 40 percent of the human genome, large regions are found to be completely devoid of retroelements. This has been hypothesised to be a result of genomic regions being intolerant to insertions of retroelements. The inadvertent transcriptional activity of retroelements may affect neighbouring genes, which in turn could be detrimental to an organism. We speculate that such retroelement transcription, or transcriptional interference, is a contributing factor in generating and maintaining retroelement-free regions in the human genome. METHODOLOGY/PRINCIPAL FINDINGS: Based on the known transcriptional properties of retroelements, we expect long interspersed elements (LINEs) to be able to display a high degree of transcriptional interference. In contrast, we expect short interspersed elements (SINEs) to display very low levels of transcriptional interference. We find that genomic regions devoid of long interspersed elements (LINEs) are enriched for protein-coding genes, but that this is not the case for regions devoid of short interspersed elements (SINEs). This is expected if genes are subject to selection against transcriptional interference. We do not find microRNAs to be associated with genomic regions devoid of either SINEs or LINEs. We further observe an increased relative activity of genes overlapping LINE-free regions during early embryogenesis, where activity of LINEs has been identified previously. CONCLUSIONS/SIGNIFICANCE: Our observations are consistent with the notion that selection against transcriptional interference has contributed to the maintenance and/or generation of retroelement-free regions in the human genome

Genome-wide association analysis of genetic generalized epilepsies implicates susceptibility loci at 1q43, 2p16.1, 2q22.3 and 17q21.32

Genetic generalized epilepsies (GGEs) have a lifetime prevalence of 0.3% and account for 20-30% of all epilepsies. Despite their high heritability of 80%, the genetic factors predisposing to GGEs remain elusive. To identify susceptibility variants shared across common GGE syndromes, we carried out a two-stage genome-wide association study (GWAS) including 3020 patients with GGEs and 3954 controls of European ancestry. To dissect out syndrome-related variants, we also explored two distinct GGE subgroups comprising 1434 patients with genetic absence epilepsies (GAEs) and 1134 patients with juvenile myoclonic epilepsy (JME). Joint Stage-1 and 2 analyses revealed genome-wide significant associations for GGEs at 2p16.1 (rs13026414, Pmeta = 2.5 × 10−9, OR[T] = 0.81) and 17q21.32 (rs72823592, Pmeta = 9.3 × 10−9, OR[A] = 0.77). The search for syndrome-related susceptibility alleles identified significant associations for GAEs at 2q22.3 (rs10496964, Pmeta = 9.1 × 10−9, OR[T] = 0.68) and at 1q43 for JME (rs12059546, Pmeta = 4.1 × 10−8, OR[G] = 1.42). Suggestive evidence for an association with GGEs was found in the region 2q24.3 (rs11890028, Pmeta = 4.0 × 10−6) nearby the SCN1A gene, which is currently the gene with the largest number of known epilepsy-related mutations. The associated regions harbor high-ranking candidate genes: CHRM3 at 1q43, VRK2 at 2p16.1, ZEB2 at 2q22.3, SCN1A at 2q24.3 and PNPO at 17q21.32. Further replication efforts are necessary to elucidate whether these positional candidate genes contribute to the heritability of the common GGE syndrome

Construction of Decision Diagrams for Product Configuration

Knowledge compilation is a well-researched field focused on translating propositional logic formulas into efficient data structures that allow polynomial-time online queries related to the SAT problem. Knowledge compilation techniques can be used to partition product configuration tasks into two distinct phases: fast online processing and slow offline preprocessing. Binary Decision Diagrams (BDDs) are widely studied in this area and provide a graph representation of Boolean formulas. However, BDD construction can be time-consuming, particularly for large instances, as their size grows exponentially with the number of variables. This paper explores methods to improve BDD construction time, including optimizing variable ordering. The evaluation involves applying these techniques to formulas in Rich Conjunctive Normal Form, comparing the results with Sentential Decision Diagrams. The experiments use CAS Software AG benchmarks.Peer reviewe

Analysis of Passive RF-DC Power Rectification and Harvesting Wireless RF Energy for Micro-watt Sensors

In this paper, analytical modeling of passive rectifying circuits and the harvesting of electromagnetic (EM) power from intentionally generated as well as from ubiquitous sources are presented. The presented model is based on the linearization of rectifying circuits. The model provides an accurate method of determining the output characteristics of rectifying circuits. The model was verified with Advance Design System (ADS) Harmonic balance (HB) simulations and measurements. The results from the presented model were in agreement with simulations and measurements. Consequently design considerations and trade-off of radio frequency (RF) harvesters are discussed. To verify the exploitation of ambient RF power sources for operation of sensors, a dual-band antenna with a size of ~λ/4 at 900MHz and a passive dual-band rectifier that is able to power a commercial Thermo-Hygrometer requiring ~1.3V and 0.5MΩ from a global system for mobile communications (GSM) base station is demonstrated. The RF power delivered by the receiving dual-band antenna at a distance of about 110 m from the GSM base station ranges from -27 dBm to -50 dBm from the various GSM frequency bands. Additionally, wireless range measurements of the RF harvesters in the industrial, scientific and medical (ISM) band 868MHz is presented at indoor conditions

Decision Heuristics in a Constraint-based Product Configurator

Publisher Copyright: © 2023 CEUR-WS. All rights reserved.This paper presents an evaluation of decision heuristics of solvers of the Boolean satisfiability problem (SAT) in the context of constraint-based product configuration. In product configuration, variable assignments are searched in real-time, based on interactively formulated user requirements. Operating on user’s successive input poses new requirements, such as low-latency interactivity as well as deterministic and minimal implicit product changes. This work presents a performance evaluation of several heuristics from the SAT literature along with new variants that address the special real-time requirements of incremental product configuration. Our results show that the execution time on an industrial benchmark can be significantly improved with our new heuristic.Peer reviewe

Direct optical detection of cell density and viability of mammalian cells by means of UV/VIS spectroscopy

The critical process parameters cell density and viability during mammalian cell cultivation are assessed by UV/VIS spectroscopy in combination with multivariate data analytical methods. This direct optical detection technique uses a commercial optical probe to acquire spectra in a label-free way without signal enhancement. For the cultivation, an inverse cultivation protocol is applied, which simulates the exponential growth phase by exponentially replacing cells and metabolites of a growing Chinese hamster ovary cell batch with fresh medium. For the simulation of the death phase, a batch of growing cells is progressively replaced by a batch with completely starved cells. Thus, the most important parts of an industrial batch cultivation are easily imitated. The cell viability was determined by the well-established method partial least squares regression (PLS). To further improve process knowledge, the viability has been determined from the spectra based on a multivariate curve resolution (MCR) model. With this approach, the progress of the cultivations can be continuously monitored solely based on an UV/VIS sensor. Thus, the monitoring of critical process parameters is possible inline within a mammalian cell cultivation process, especially the viable cell density. In addition, the beginning of cell death can be detected by this method which allows us to determine the cell viability with acceptable error. The combination of inline UV/VIS spectroscopy with multivariate curve resolution generates additional process knowledge complementary to PLS and is considered a suitable process analytical tool for monitoring industrial cultivation processes

Cleaning in place concept for continuous operation of optical probes in process analytics of polymer extrusion

Die kontinuierliche Erfassung von Qualitätsparametern ist eine zunehmende Anforderung in der Polymerextrusion. Die optische Spektroskopie kann diese Anforderung erfüllen, da sie neben der Farbe weitere Parameter wie beispielsweise chemische Eigenschaften, Trübungsgrad oder Partikelgröße erfasst. Dabei werden für Inline-Messungen im Extruder optische Sonden eingesetzt. Im laufenden Betrieb bilden sich Ablagerungen auf den Sondenfenstern. Dieser Beitrag präsentiert ein neues Cleaning in Place Konzept, mit dessen Hilfe die Fenster auch während der Produktion ohne Unterbrechung gereinigt werden können. Auch die Kalibrierung der Messtechnik ist dabei möglich. Das verhindert Rüstzeiten und sichert eine kontinuierliche Inline-Messung.The continuous monitoring of quality parameters is an increasing requirement in polymer extrusion. Optical spectroscopy can fulfill this requirement as it detects other parameters besides color, such as chemical properties, turbidity or particle size. Here, optical probes are used for inline measurements in the extruder. During operation, material can accumulate on the probe windows (window fouling). This article presents a new cleaning in place concept that allows windows to be cleaned without interruption during production. Additionally, the calibration of the measurement system is possible. This prevents set-up times and ensures a continuous inline measurement