On the part inventory model sequencing problem: complexity and Beam Search heuristic

In many industries mixed-model assembly systems are increasingly supplied out of third-party consignment stock. This novel trend gives rise to a new short-term sequencing problem which decides on the succession of models launched down the line and aims at minimizing the cost of in-process inventory held by the manufacturer. In this work, we investigate the mathematical structure of this part oriented mixed-model sequencing problem and prove that general instances of the problem are NP-hard in the strong sense. Moreover, we develop a new Beam Search heuristic, which clearly outperforms existing solution procedures.     

Elucidation of Phosphatidylcholine Composition in Krill Oil Extracted from <Emphasis Type="Italic">Euphausia superba</Emphasis>

High performance liquid chromatography-electrospray tandem mass spectrometry was used to elucidate the phospholipids in krill oil extracted from Euphausia superba, an emerging source for human nutritional supplements. The study was carried out in order to map the species of the choline-containing phospholipid classes: phosphatidylcholine and lyso-phosphatidylcholine. In addition, the prevalent phosphatidylcholine class was quantified and the results compared with prior analysis. The qualification was performed with separation on a reverse phase chromatography column, while the quantification was obtained with class separation on a normal phase chromatography column. An Orbitrap system was used for the detection, and pulsed-Q dissociation fragmentation was utilized for the identification of the species. An asymmetrical exclusion list was applied for detection of phospholipid species of lower concentration, significantly improving the number of species observed. A total of 69 choline-containing phospholipids were detected, whereof 60 phosphatidylcholine substances, among others seven with probable omega-3 fatty acids in both sn-1 and sn-2. The phosphatidylcholine concentration was estimated to be 34 ± 5 g/100 g oil (n = 5). These results confirm the complexity of the phospholipid composition of krill oil, and the presence of long chained, heavily unsaturated fatty acids.     

Alumina–Aluminide Alloys (3A) Technology: I, Model Development

The general reaction behavior of the 3A process under the thermal explosion mode of synthesis has been investigated via a continuum model. The continuum model uses mass and energy balances to predict temperature difference ( T _s,avg− T _f) curves, as well as profile curves of the reactant conversions and sample temperature. In particular, the effect of the dimensionless parameters associated with the rate of local heat generation (β, the thermicity factor), the activation energy (γ, the Arrhenius number), the rate of heat redistribution (α, the modified thermal diffusivity), the rate of heat transfer by convection (Bi, the Biot number or convective heat transfer parameter), and the rate of heat transfer by radiation (Ω, the radiative heat transfer parameter) were investigated. Conditions to control the reaction process, which should produce high-density final products, were determined. It was found that the overall maximum temperature may be reduced for high γ, low β, high α, and high Bi and Ω. In terms of processing conditions, this may be obtained by reducing the initial reactant concentrations, optimizing the particle size, using small sample sizes and high compaction pressure, and increasing the heat loss by using a high thermal conductivity inert gas.     

Hydrophobicity engineering of cholera toxin A1 subunit in the strong adjuvant fusion protein CTA1-DD

Protein engineering of the cholera toxin A1 subunit (CTA1) fusedto a dimer of the Ig-binding D-region of Staphylococcus aureusprotein A (DD) was employed to investigate the effect of specificamino acid changes on solubility, stability, enzymatic activityand capacity to act as an adjuvant in vivo. A series of CTA1-DDanalogues were selected by a rational modeling approach, inwhich surface-exposed hydrophobic amino acids of CTA1 were exchangedfor hydrophilic counterparts modeled for best structural fit.Of six different mutants initially produced, two analogues,CTA1Phe132Ser-DD and CTA1Pro185Gln-DD, were demonstrated tohave 50 and 70% increased solubility, respectively, at neutralpH. The double mutant CTA1Phe132Ser/Pro185Gln-DD was at leastthreefold more soluble, demonstrating an additive effect ofthe two mutations. Only the Phe132Ser analogue retained fullbiological activity and stability compared with the native CTA1-DDfusion protein. Two mutants, Pro185Gln and Phe31His mutations,exhibited unaltered ADP-ribosyltransferase activity in vitro,but demonstrated markedly reduced adjuvant function. Since thePro185 and Phe31 amino acids are located in close vicinity onthe distal side of the molecule relative to the enzymaticallyactive cleft, it is conceivable that this region is involvedin mediating a biological function, separate from the enzymaticactivity but intrinsic to the adjuvant activity of CTA1.     

Commercially available alternatives to palm oil

Since several years there has been a demand for food products free of palm oil, noticeable in the Western European market. Alternatives based on liquid oils, fully hydrogenated fats, and exotic fats like shea and sal etc., have been developed by the research groups of several specialty oils and fats suppliers. This article describes the advantages and disadvantages of those products and compares them to similar products based on palm oil. It is also discussed how reasonable the replacement of palm products would be, since sustainable and 3‐MCPD/glycidolester‐reduced palm based specialty oils are also available on the market.     

Pedestrian crossing situations: Quantification of comfort boundaries to guide intervention timing

Introduction

Technical systems that warn or brake for vehicle–pedestrian encounters reduce injuries more effectively the earlier an intervention is initiated. However, premature intervention can irritate drivers, leading to system deactivation and, consequently, no injury reduction whatsoever. It has been proposed that no intervention should be initiated as long as attentive drivers are within their comfort zones. This study aims at quantifying driver comfort boundaries for pedestrian crossing situations to offer guidance for the appropriate timing of interventions.

Methods

Sixty two volunteers drove through an intersection on a test track at 30 and 50 km/h. A pedestrian dummy was launched from behind an obstruction towards the driving path of the approaching car. Brake onset indicated discomfort. Time to collision (TTC), longitudinal and lateral distance were measured at brake onset.

Results

TTC was independent of driving speed ranging from 2.1 to 4.3 s with a median of 3.2 s. Longitudinal distance ranged from 19 to 48 meters with an apparent difference between driving speeds. Lateral distances differed slightly, but significantly between driving speeds. The median was 3.1 m (3.2 m for 30 km/h and 2.9 m for 50 km/h) and values ranged from 1.9 to 4.1 m. Lateral distance in seconds ranged from 1.9 to 4.3 s with a median value of 3.1 s (3.2 s for 30 km/h and 3.0 s for 50 km/h).

Discussion

TTC was independent of driving speed, trial order and volunteer age. It might be considered suitable to intervene in situations where, for example, 90% of drivers have exceeded their comfort boundary, i.e. when drivers have already initiated braking. This percentile value translates to intervention at a TTC of 2.5 s (95% confidence 2.4–2.7 s). The study was limited to Swedish nationals, fully aware drivers, and two driving speeds, but did not investigate behavioural changes due to system interaction.

Conclusion

This study showed that TTC at brake onset was a suitable measure for the quantification of driver comfort boundaries in pedestrian crossing situations. All drivers applied their brakes prior to 2.1 s TTC.     

Distance and velocity measures: using citations to determine breadth and speed of research impact

Research that integrates the social and natural sciences is vital to address many societal challenges, yet is difficult to arrange, conduct, and disseminate. This paper compares diffusion of the research supported by a unique U.S. National Science Foundation program on Human and Social Dynamics (“HSD”) with a matched group of heavily cited papers. We offer a measure of the distance of cites between the Web of Science Category (“WoSC”) in which a publication appears and the WoSC of the journal citing it, and find that HSD publications are cited more distantly than are comparison publications. We provide another measure—citation velocity—finding that HSD publications are cited with similar lag times as are the comparison papers. These basic citation distance and velocity measures enrich analyses of research knowledge diffusion patterns.