CONCURRENT PATH CONSTRUCTION FOR GLOBAL MAP BUILDING IN UNKNOWN INDOOR ENVIRONMENTS

The map building problem is the most fundemental issue in intelligent mobile robot reasearch. Several map construction methods have been proposed, but most of them require a predefined path before the construction of an environment map. In this study, a novel concurrent path construction algorithm for map building problem in a completely unknown indoor environment is presented. In the concurrent path construction task, the main idea is based on a lookahead strategy that estimates the next location where the robot will go, using its latest state and range readings. A local map is derived from the readings of 2D range-finders and line segments constituting the local map are also used to update a global map. A significant feature of this study is that it does not reqire a predefined path for navigation to construct an environment map. Moreover, optimum sensor readings are aimed to decrease the data processing time needed for a complete map construction by reducing the number of range readings from the surroundings. Simulation results on widely used and custom indoor architectures demonstrate that the proposed approach generates highly efficient paths and global maps for all handled problem instances.     

Atmospheric pressure plasma jet treatment of wheat straw for improved compatibility in epoxy composites

The aim of this study was to investigate the effects of an atmospheric‐pressure gas plasma jet treatment on the interior and exterior surface characteristics of wheat straw and on the mechanical properties of epoxy composites reinforced with wheat straw. Dry air was used as the process gas in the plasma system. A distance between the nozzle and the substrate surface (DNSS) of 35 mm was determined as the most effective parameter enabling remarkable decreases in the (surface energy) values of both the interior and exterior surfaces of virgin wheat straw. Increased intensities of the peaks related to carbon‐rich species and 11% to 43% decreases in the oxygen/carbon ratios on the surfaces confirmed the more hydrophobic nature of the plasma‐treated wheat straw. A further increase in the DNSS decreased the effectiveness of the plasma treatment, while a decrease in the DNSS caused an inverse effect on the value, probably due to the etching effect of the plasma action, which was supported by the atomic force microscopy analysis. The overall results indicated that the increased hydrophobicity and valley‐like occurrences without sharp pits created by the plasma action improved the compatibility of the wheat straw with the epoxy matrix, which contributed to superior mechanical properties of the composites. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45828.     

High temperature-tolerant tomato lines: bioactive compounds

High global temperatures will be a great challenge for agricultural production in the near future. Therefore, adaptation of agricultural crops to the high temperatures or development of new heat-tolerant crops with known bioactive compounds is an important strategy for nutritional health and crop improvement programs. In this context, the bioactive compounds of newly developed high temperature-tolerant tomato lines were investigated in terms of lycopene, β-carotene, ascorbic acid and phenolic compounds to assist breeders for the selection of high temperature tolerant tomato varieties with high nutritional quality. Nineteen tomato lines, including control varieties from the “Turkey F1 Hybrid vegetable variety and quality line development” project and the GAP Agricultural Research Institute, were selected for the investigation. Line 11 was superior in lycopene and β-carotene content, while line 18 was superior in ascorbic acid content as compared to control varieties Cansun F1 and Alsancak RN F1. Urfa 2012 and line 28 were found to have the highest numbers of phenolic compounds. Chlorogenic acid, naringenin, trans-ferulic acid and rutin were key phenolic compounds detected in each of the tomato lines. These newly released tomato lines can be used as value-added germplasm or parent sources to develop new heat-tolerant cultivars in breeding programs or as commercial cultivars for their superior functional qualities.     

The early implementation of failure modes into existing component model libraries

This research addresses a need in systems engineering to verify that a system can meet performance requirements; this is done by integrating failure behavior into the system’s nominal model during the initial stages of design. In general, failure behavior is not used in early assessments, lending toward increased uncertainty in the model’s validity. Current libraries do not model failures and thus cannot confidently address how a design will function in the intended operational environments. Since failures occur from effects on the environment, they should be included during verification and validation efforts. Current approaches capture off-nominal behavior using parameter variation where flow variables and parameters are varied to measure the system-level effect. This approach is ad hoc and does not accurately capture failure mode behavior. To address this limitation, an approach is developed to understand and implement failure mode behavior into nominal models. The Modelica Standard Library (MSL) is used as an example for the component library of nominal models. MSL has a significant amount of basic nominal component behavior and therefore is desirable for this research. Two approaches are developed to implement failure mode behavior; the first uses transfer function and use case graphs, and the second uses existing literature. In addition, complex systems often have a large number of components and an even larger number of failure modes. Since the goal is to limit the development time, we generate an approach to identify high-risk failure modes. This captures an early system-level effect of each failure mode and uses an occurrence to calculate risk. To show the usefulness of each method, two examples are provided including a vehicle drivetrain subsystem with a variety of failures and a diesel engine with fuel injector and valve failures.     

Development and in vitro evaluation of pH-independent release matrix tablet of weakly acidic drug valsartan using quality by design tools

Abstract

The main objective of this study was the development of pH-independent controlled release valsartan matrix tablet in Quality by design (QbD) framework. The quality target product profile (QTPP), critical quality attributes (CQAs) and critical material attributes (CMAs) were defined by science and risk-based methodologies. Potential risk factors were identified with Fishbone diagram. Following, CMAs were further investigated with a semi-quantitative risk assessment method, which has been revised with mitigated risks after development and optimization studies. According to defined critical material attributes, which one of them was determined to be the dissolution, formulation optimization study was performed by using a statistical design of experiment. Formulation variables have been identified and fixed first with a ‘One factor at a time (OFAT)’ approach. After OFAT studies, a statistical experimental design was conducted with the most critical material attributes. Statistical design space and mathematical prediction equations have been developed for dissolution and hardness, which is important to predict drug dissolution behavior. In conclusion, a pH-independent release has been achieved for weakly acidic drug valsartan with a deeper understanding of drug product quality, with the science and risk-based approaches of QbD tools.     

Performance of International Joint Ventures in Construction

International joint ventures (IJVs) have become popular because of their importance as a strategic alternative in global competition. The measurement of the performance of IJVs has been an important research topic for a few decades, however there is no consensus on an appropriate definition and measurement of IJV performance. In this study, a model is proposed to assess IJV performance in construction. The validity of the proposed drivers and measures of performance is investigated and relationships between them are analyzed. The effects of interpartner fit/relations, structural IJV characteristics, host country factors, and project-related factors on IJV performance are examined through a questionnaire survey. IJV performance is defined by a four-dimensional construct that considers the performance of the project, the IJV partners, the IJV organization itself, and the perceptions of the IJV partners. The results point out the significance of the interpartner fit and the quality of partner relations for a successful IJV operation. The findings of the study also suggest that project-related factors have a moderate influence on IJV performance. In a properly designed IJV structure, partners with compatible skills, resources, and cultures are found to maintain good relations and are expected to achieve greater IJV success.     

Single‐chain polymer nanoparticles via click crosslinking and effect of photoinduced radical combination on crosslink points

Folding of azide functionalized polymer chains was obtained via the copper‐catalyzed azide alkyne cycloaddition (CuAAC) methodology using a light‐responsive crosslinker as the ‘click’ component. Subsequently, crosslinked junction points were combined with a photoinduced radical combination strategy to achieve more compact nanoparticles. The resultant folding particles possess smaller particle sizes and higher glass transition temperature values compared to their linear analogues. Fourier transform IR spectroscopy, SEC, DSC, dynamic light scattering, ¹H NMR and TEM techniques were used for characterization. © 2020 Society of Chemical Industry