A New Quasi-Human Algorithm for Solving the Packing Problem of Unit Equilateral Triangles

The packing problem of unit equilateral triangles not only has the theoretical significance but also offers broad prospects in material processing and network resource optimization. Because this problem is nondeterministic polynomial (NP) hard and has the feature of continuity, it is necessary to limit the placements of unit equilateral triangles before optimizing and obtaining approximate solution (e.g., the unit equilateral triangles are not allowed to be rotated). This paper adopts a new quasi-human strategy to study the packing problem of unit equilateral triangles. Some new concepts are put forward such as side-clinging action, and an approximation algorithm for solving the addressed problem is designed. Time complexity analysis and the calculation results indicate that the proposed method is a polynomial time algorithm, which provides the possibility to solve the packing problem of arbitrary triangles

A New Quasi-Human Algorithm for Solving the Packing Problem of Unit Equilateral Triangles

The packing problem of unit equilateral triangles not only has the theoretical significance but also offers broad prospects in material processing and network resource optimization. Because this problem is nondeterministic polynomial (NP) hard and has the feature of continuity, it is necessary to limit the placements of unit equilateral triangles before optimizing and obtaining approximate solution (e.g., the unit equilateral triangles are not allowed to be rotated). This paper adopts a new quasi-human strategy to study the packing problem of unit equilateral triangles. Some new concepts are put forward such as side-clinging action, and an approximation algorithm for solving the addressed problem is designed. Time complexity analysis and the calculation results indicate that the proposed method is a polynomial time algorithm, which provides the possibility to solve the packing problem of arbitrary triangles

High brilliant diode laser light source on the base of hybrid oscillator-amplifier systems

Eine der aktuellen Herausforderungen für die Forschung auf dem Gebiet der Halbleiterlaser Lichtquellen ist es, hohe optische Leistungen im Wattbereich mit beugungsbegrenzter Strahlqualität und spektral stabilisierter, schmalbandiger Emission zu vereinen. Jede Verbesserung erlaubt neue Anwendungen für die Materialbearbeitung, optische Freiraumkommunikation, in der Displaytechnologie und in der LIDAR-Technik. Wesentliche Fortschritte konnten diesbezüglich mit Master-Oscillator Power-Amplifier (MOPA)-Systemen erreicht werden, deren Endstufe auf optischen Halbleiterverstärkern mit einem großflächigen Verstärkungsgebiet beruht. Ein Laser (MO) liefert eine spektral schmalbandige Emission mit beugungsbegrenzter Strahlqualität. Dessen relativ niedrige optische Leistung wird in den Verstärker (PA) mit einer sogenannten abgeschnittenen (truncated) trapezförmigen Kontaktfläche eingekoppelt. Dieses Design ermöglicht eine hohe optische Leistung und eine zugleich gute Strahlqualität. Ziel dieser Doktorarbeit ist es, durch die systematische Untersuchung des Einflusses unterschiedlicher Kontaktgeometrien, verschiedener Schichtstrukturen für dieWellenführung und der Anzahl von Quantenfilmen auf die elektro-optischen Eigenschaften ein optimiertes Design für den Verstärker und somit eine fortgeschrittene Halbleiterlaserlichtquelle zu realisieren. Im ersten Teil der Arbeit werden im Wesentlichen theoretische Aspekte und das Funktionsprinzip des MOPA-Systems erläutert, wobei der Schwerpunkt auf den Trapezverstärker gelegt wird. Das Design und der Schichtaufbau des Halbleiterchips und dessen Montage werden vorgestellt. Da ein wesentlicher Teil dieser Arbeit der Verbesserung der Strahlqualität des Verstärkers gewidmet ist, werden die Strahlparameter und die Kriterien, mit denen die Strahlqualität des Verstärkers bewertet wird, ausführlich diskutiert. Die experimentelle Realisierung des MOPA-Systems einschließlich der Art und Weise der Einkopplung des Strahls in den Verstärker wird vorgestellt. Letzteres spielt eine wichtige Rolle bei den Untersuchungen. Der zweite Teil der Arbeit beinhaltet die experimentellen Untersuchungsergebnisse (Leistungs-Strom-Kennlinien, optische Spektren, Strahlqualität) der für eine Emissionswellenlänge von 970nm designten Verstärker unterschiedlicher Schichtstrukturen und Geometrie. Beim Design der Schichtstruktur für den Verstärker spielen niedrige optische Verluste sowie ein auf die Leistung des MOs und der Länge des Verstärkers abgestimmter optischer Gewinn die entscheidende Rolle: Der Gewinn muss zwar hinreichend groß für eine ausreichende Verstärkung sein, darf aber eine bestimmte Größe nicht überschreiten, damit sich die Strahlqualität nicht verschlechtert. Mit einer optimierten Kontaktgeometrie ist es gelungen, mehr als 17W beugungsbegrenzte optische Leistung aus einzelnen Verstärkern im Quasi-Dauerstrichbetrieb zu erreichen. Die maximal erzielte Gesamtleistung mit einer spektralen Bandbreite von 30pm betrug mehr als 50W. Abschließend werden Möglichkeiten für weitere Optimierungen der Verstärker diskutiert.One of the current challenges in the development of semiconductor-based light sources is to combine optical powers in the watt class with diffraction-limited beam quality and spectrally stable and narrow-band emission. Every improvement enables new applications in material processing, optical free-space communication, as well as in display and LIDAR technology. Significant progress has recently been achieved in this field using „Master-Oscillator-Power-Amplifier“ (MOPA) systems. The output stage is based on a semiconductor optical amplifier with a large-area gain region. The MO produces spectrally narrow emission, with diffraction limited beam quality. The relatively low optical emission from the MO is coupled into the amplifier. The amplifier (PA) has an electrically pumped area with a so-called ttruncatedttaper-profile. This design enables a high output power and at the same time good beam quality. The aim of this Ph.D. work is to realize an optimized design for the amplifier and thus an advanced light source by means of variations to the geometry of the pumped area, vertical wave guide and the number of quantum wells. The first part of this work is focused on the theory and the operating principles of MOPA-systems and their key component, the tapered amplifier. The design and construction of the amplifier is outlined, including the whole process from epitaxy to packaging. As a main objective of this work is to improve the beam quality of the device, the beam parameters and the criteria with which the beam quality is evaluated, are discussed extensively. The experimental setup is explained in detail, especially the coupling method, which plays a significant role in the studies. The realization of an advanced laser light source based on MOPA-systems in the second part of this work presents experimental results (light-current-characteristics, optical spectra, beam quality) for amplifiers of different epitaxy structures and geometries designed for an emission wavelength of 970nm. Low optical loss and a tailored modal gain are both critical factors in the design of semiconductor structures for use in such amplifiers, with the gain matched to the output of the MO and the length of the device. The gain must produce sufficient amplification; however if gain is too large the beam quality is degraded. Moreover, the opto-electronic performance of the amplifier also depends strongly on the device geometry. Optimized semiconductor layer structures have been successfully developed that allow single amplifiers to achieve more than 17W diffraction limited optical output under quasi-continuous-wave conditions. A total power of more than 50W was emitted within a narrow spectral band of 30pm. Finally, options for further performance improvements are presented

Effects of Different Root Zone Heating Methods on the Growth and Photosynthetic Characteristics of Cucumber

Root zone heating can solve the problems associated with the yield and decline in the quality caused by low-temperature stress in cucumber during winter and early spring. An experiment was performed to investigate the effects of different heating methods on the root zone temperature, growth and photosynthetic characteristics, fruit quality, and yield of cucumber. Using traditional soil cultivation (CK1) and sand cultivation (CK2) in a greenhouse as the controls, four heating treatments were set up: soil-ridge sand-embedded cultivation (T1), water-heated soil cultivation (T2), water-heated sand cultivation (T3), and water-curtain and floor-heating cultivation (T4). The results indicated that heating treatments T2 and T4 had better warming and insulation effects than the other treatments during both day and night, with an average temperature increase throughout the day of 0.8–1.2 °C compared with CK1. The chlorophyll content of leaves under the T2 and T4 treatments increased, and the photosynthetic rate and the overall plant growth were significantly higher than in the other treatments. Compared with the control, the fruit yield increased most significantly under the T2 and T4; the soluble sugar, soluble solids, and Vc contents in the fruit increased; while the nitrate content in the fruit decreased, effectively improving the fruit’s quality and yield. It was finally determined that the T2 and T4 heating treatments are the most effective in solving the low-temperature problem. Moreover, as T2 consumed relatively more electricity, the use of a water-curtain and floor-heating system in winter and spring should be considered in order to boost the yield and improve the quality

Effects of Different Root Zone Heating Methods on the Growth and Photosynthetic Characteristics of Cucumber

Root zone heating can solve the problems associated with the yield and decline in the quality caused by low-temperature stress in cucumber during winter and early spring. An experiment was performed to investigate the effects of different heating methods on the root zone temperature, growth and photosynthetic characteristics, fruit quality, and yield of cucumber. Using traditional soil cultivation (CK1) and sand cultivation (CK2) in a greenhouse as the controls, four heating treatments were set up: soil-ridge sand-embedded cultivation (T1), water-heated soil cultivation (T2), water-heated sand cultivation (T3), and water-curtain and floor-heating cultivation (T4). The results indicated that heating treatments T2 and T4 had better warming and insulation effects than the other treatments during both day and night, with an average temperature increase throughout the day of 0.8–1.2 °C compared with CK1. The chlorophyll content of leaves under the T2 and T4 treatments increased, and the photosynthetic rate and the overall plant growth were significantly higher than in the other treatments. Compared with the control, the fruit yield increased most significantly under the T2 and T4; the soluble sugar, soluble solids, and Vc contents in the fruit increased; while the nitrate content in the fruit decreased, effectively improving the fruit’s quality and yield. It was finally determined that the T2 and T4 heating treatments are the most effective in solving the low-temperature problem. Moreover, as T2 consumed relatively more electricity, the use of a water-curtain and floor-heating system in winter and spring should be considered in order to boost the yield and improve the quality

Drug resistance and combating drug resistance in cancer

Cancer is the second leading cause of death in the US. Current major treatments for cancer management include surgery, cytotoxic chemotherapy, targeted therapy, radiation therapy, endocrine therapy and immunotherapy. Despite the endeavors and achievements made in treating cancers during the past decades, resistance to classical chemotherapeutic agents and/or novel targeted drugs continues to be a major problem in cancer therapies. Drug resistance, either existing before treatment (intrinsic) or generated after therapy (acquired), is responsible for most relapses of cancer, one of the major causes of death of the disease. Heterogeneity among patients and tumors, and the versatility of cancer to circumvent therapies make drug resistance more challenging to deal with. Better understanding the mechanisms of drug resistance is required to provide guidance to future cancer treatment and achieve better outcomes. In this review, intrinsic and acquired resistance will be discussed. In addition, new discoveries in mechanisms of drug resistance will be reviewed. Particularly, we will highlight roles of ATP in drug resistance by discussing recent findings of exceptionally high levels of intratumoral extracellular ATP as well as intracellular ATP internalized from extracellular environment. The complexity of drug resistance development suggests that combinational and personalized therapies, which should take ATP into consideration, might provide better strategies and improved efficacy for fighting drug resistance in cancer

Where Will ‘Water-Energy-Food’ Research Go Next?—Visualisation Review and Prospect

Research on water, energy, and food (WEF) is gradually becoming a global research hotspot in response to threats caused by the overexploitation of resources. In this study, 13,202 documents were selected from the WoS database and CiteSpace to judge frontier development in WEF research. In this study, visualisation research was carried out in 1547 papers that are most relevant to WEF research. The results show that WEF research has gradually increased during the research period, especially since 2015. The Food and Agriculture Organisation of the United Nations, Hoff, and Bazilian have the greatest influence on the promotion of WEF research and there is significant cooperation between institutions and countries. The United States, China, and the United Kingdom were the main contributors. The WEF nexus has become the most important hotspot in WEF research. In this case, 823 papers focused on the WEF nexus were selected to demonstrate the research contents, frontiers and clusters, and methods of the WEF nexus. Applied researches on the WEF nexus, such as security issues and multi-objective optimisation are current frontiers. Some new topics such as the pandemic and geopolitics have not attracted enough attention relative to their potential importance. A comprehensive data platform for the inter-department of water, energy, and food subsystems should be constructed in the near future

A Heuristic Algorithm for Solving Triangle Packing Problem

The research on the triangle packing problem has important theoretic significance, which has broad application prospects in material processing, network resource optimization, and so forth. Generally speaking, the orientation of the triangle should be limited in advance, since the triangle packing problem is NP-hard and has continuous properties. For example, the polygon is not allowed to rotate; then, the approximate solution can be obtained by optimization method. This paper studies the triangle packing problem by a new kind of method. Such concepts as angle region, corner-occupying action, corner-occupying strategy, and edge-conjoining strategy are presented in this paper. In addition, an edge-conjoining and corner-occupying algorithm is designed, which is to obtain an approximate solution. It is demonstrated that the proposed algorithm is highly efficient, and by the time complexity analysis and the analogue experiment result is found

Sodium Silicate Improves Cucumber Seedling Growth and Substrate Nutrients and Reduces Heavy Metal Accumulation in Plants

The gasification filter cake (GFC) has great application potential for improving the characteristics of seedling substrates due to its nutrient richness and excellent water retention capacity. However, GFCs leach heavy metals easily and thus pose certain ecological risks. Sodium silicate can enhance plant resistance to heavy metal toxicity by fixing heavy metals. This study investigated the impact of sodium silicate on cucumber plant growth, the chemical characterization of the substrate, and the distribution and transfer of heavy metals. Sodium silicate was added to the seedling substrate mix at mass rates of 0 g/kg−1 (GFC0), 2 g/kg−1 (GFC2), 4 g/kg−1 (GFC4), and 8 g/kg−1 (GFC8). The seedling substrate was composed of a commercial matrix, caragana compost, and GFC (m:m 7:7:2). The GFC increased the content of total phosphorus (P), available phosphorus (P), and available potassium (K) in the substrate by 31.58%, 16.58%, and 80.10%, respectively. Conversely, the GFC decreased the plant height by 12.3%. Adding sodium silicate to the GFC increased the chlorophyll content of the plants, fixed heavy metals in the substrate, and promoted nutrient absorption and utilization by the plants. Compared with GFC0 without sodium silicate, adding sodium silicate at a mass rate of 2 g/kg−1 (GFC2) reduced the chromium, lead, and cadmium contents by 51.13%, 26.37%, and 90.04%, respectively, which effectively alleviated heavy metal stress and was more conducive to plant growth