The origin, evolution, and application of the megapolitan area concept

Robert E. Lang,임재원,Karen A. Danielsen 서울시립대학교 도시과학연구원 2020 도시과학국제저널 Vol.24 No.1

The article explores the origin and evolution of the ‘megapolitan concept', the idea of a super-sized region that began in 1961 in Jean Gottmann's ‘megalopolis,' which he developed to explain large-scale urbanization in the Northeastern U.S. Jerome Picard, a researcher at the Urban Land Institute took up the megalopolis idea in 1967 and applied it to the entire U.S. and projected large-scale urban growth to 2000. The Regional Plan Association (RPA) also applied the megalopolis concept to The Second Regional Plan for New York in 1968. Lang in 2000s, then working with his colleagues at Virginia Tech developed the megapolitan concept and definition-in part to differential the concept from work being done by the University of Pennsylvania for RPA. Lang defined ‘megapolitan clusters’ as multiple megapolitan areas that are networked either by commuting, logistics, or dense air links, but where there is no more than three times the distance used to define a Megapolitan Area between anchor metropolitan areas at their furthest distance. The recent evolution of megapolitan area and megapolitan cluster concepts by Lang and the colleagues is applied to a series of projects, including ‘Sun Corridor’ in 2006 (Phoenix-Tucson) and the Southwest Triangle (SoCal-Sun Corridor-Las Vegas) in 2014. The article ends with the future application of megapolitan area concept in the rapidly growing Southwest Triangle megapolitan cluster.

Learning Multiple-Gait Quadrupedal Locomotion via Hierarchical Reinforcement Learning

Lang Wei,Yunxiang Li,Yunfei Ai,Yuze Wu,Hao Xu,Wei Wang,Guoming Hu 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.24 No.9

Over long periods of evolution, legged animals have developed the capability to use a variety of gaits to move efficiently and flexibly at different speeds. To enable quadruped robots to acquire this ability, this study proposes a two-stage training hierarchical framework that can have quadruped robots generate energy-efficient multiple-gait locomotion, consisting of a gait selection policy module and a react controller module. The parameters of both modules are optimized using reinforcement learning. The experimental results in the simulation demonstrate that the proposed method can generate energy-efficient multiple-gait quadrupedal locomotion compared to previous methods. To validate the robustness and effectiveness of the method, we constructed a closed-chain quadruped robot and deployed the controller trained by the method to the robot. The experimental results in the real world suggest that the controller can enable the robot to move stably and efficiently in different gaits. The main contribution of this paper is that the authors propose a novel hierarchical framework, which makes quadruped robots use an optimal gait at a specific speed and smoothly switch to another one after getting a different speed command. These behaviors are automatically produced through simulation training, eliminating the need for the tedious work of designing gaits and modulating controllers. Experimental results showcase that the proposed method has significant advantages compared to previous methods.

Opioid-induced constipation: a narrative review of therapeutic options in clinical management

Lang-Illievich, Kordula,Bornemann-Cimenti, Helmar The Korean Pain Society 2019 The Korean Journal of Pain Vol.32 No.2

Pain therapy often entails gastrointestinal adverse events. While opioids are effective drugs for pain relief, the incidence of opioid-induced constipation (OIC) varies greatly from 15% to as high as 81%. This can lead to a significant impairment in quality of life, often resulting in discontinuation of opioid therapy. In this regard, a good doctor-patient relationship is especially pivotal when initiating opioid therapy. In addition to a detailed history of bowel habits, patient education regarding the possible gastrointestinal side effects of the drugs is crucial. In addition, the bowel function must be regularly evaluated for the entire duration of treatment with opioids. Furthermore, if the patient has preexisting constipation that is well under control, continuation of that treatment is important. In the absence of such history, general recommendations should include sufficient fluid intake, physical activity, and regular intake of dietary fiber. In patients of OIC with ongoing opioid therapy, the necessity of opioid use should be critically reevaluated in terms of an with acceptable quality of life, particularly in cases of non-cancer pain. If opioids must be continued, lowering the dose may help, as well as changing the type of opioid. If these measures do not suffice, the next step for persistent OIC is the administration of laxatives. If these are ineffective as well, treatment with peripherally active ${\mu}$-opioid receptor antagonists should be considered. Enemas and irrigation are emergency measures, often used as a last resort.

Can Managerial Military Experience Affect Corporate Innovation? : Evidence from an Emerging Market

Lang, Xiangxiang,You, Dandan,Cui, Li,Peng, Zhe Institute of Management Research 2020 Journal of East Asia Management Vol.1 No.1

Military experience has a great impact on a soldier ability to handle risks. Therefore, when those soldiers become managers, they may behave differently in making risky corporate decisions, especially in activities like the R&D investment. However, studies on how military experience affect R&D have been largely missing in the largest emerging economy, i.e. China, despite that the country hires a higher percentage of military managers than the US. In addition, it remains a question whether military managers affect the state-owned enterprises (SOEs) in China, as many of the corporate decisions are made by the government. This paper tries to address these questions. The imprinting theory and the upper echelon theory suggest that managers' personal experience can affect their behaviour, which in turn influences their corporate decisions. In this paper, we examine whether managers with military experience lead to higher R&D investment and whether such an effect exists in state-owned enterprises. Based on a sample of listed firms in China's A-share market over 2008-2017, we make two findings. First, companies with military managers have high R&D investment. By dividing managers' military positions into high and low rank, we find that companies tend to have higher (lower) R&D investment if their managers hold a high-rank (low-rank) position. Second, the effect of high-rank military managers on R&D investment is more pronounced if the manager is also the founder and the company is a non-state-owned enterprise. For low-ranking military managers, a stronger effect on R&D investment is also observed if they are also the founder, but whether their companies are state-owned or not has no impact on R&D investment. This study identifies managers' military experience as a contributing factors to corporate R&D investment in the largest emerging economy. This paper tests an implication of the imprinting theory and the upper echelon theory, i.e., managers' personal experience can affect their behaviour, which in turn influences their corporate decisions. Specifically, we focus on one aspect of personal experience - military experience - and look at whether it is beneficial to firms' technological innovation, therefore enriches the literature of managerial heterogeneity. Our findings on the influence of managers' military experience on firms' technological innovation can help us better understand the role of managers play in corporate decision making, and how managers' individual traits interact with the firm's characteristics.

A Robust Method for Speech Replay Attack Detection

( Lang Lin ),( Rangding Wang ),( Diqun Yan ),( Li Dong ) 한국인터넷정보학회 2020 KSII Transactions on Internet and Information Syst Vol.14 No.1

Spoofing attacks, especially replay attacks, pose great security challenges to automatic speaker verification (ASV) systems. Current works on replay attacks detection primarily focused on either developing new features or improving classifier performance, ignoring the effects of feature variability, e.g., the channel variability. In this paper, we first establish a mathematical model for replay speech and introduce a method for eliminating the negative interference of the channel. Then a novel feature is proposed to detect the replay attacks. To further boost the detection performance, four post-processing methods using normalization techniques are investigated. We evaluate our proposed method on the ASVspoof 2017 dataset. The experimental results show that our approach outperforms the competing methods in terms of detection accuracy. More interestingly, we find that the proposed normalization strategy could also improve the performance of the existing algorithms.

Co‑doped amorphous MoSx for efficient hydrogen evolution reaction in acid condition

Lang Gan,Jincheng Liu,Yanjie Ren,Zhongyi Xiong,Kang Chen 한국탄소학회 2023 Carbon Letters Vol.33 No.5

Amorphous molybdenum sulfide ( MoSx) has been regarded as a promising hydrogen evolution reaction (HER) catalyst due to its mild preparation conditions and low-cost precursor materials. In this work, we report a simple strategy combining the growth of amorphous MoSx on the surface of metal organic frameworks (ZIF-67) and annealing treatment to prepare Co-doped MoSx nanopolyhedrons (denoted as CoMoSx NPs). The CoMoSx NPs exhibit excellent HER activity in acid condition with an overpotential of 188 mV at a current density of 10 mA cm? 2 (η10), and a relatively stable overpotential after 2000 cyclic voltammetry (CV) cycles testing. The excellent HER performance of the CoMoSx NPs can be attributed to the doping of Co element adjust the electronic structure and increase the conductivity of catalyst, and the nanopolyhedrons structure which can expose more active sites for HER electrocatalytic. This study offers a low-cost and simple strategy to prepare high-activity HER catalyst, which holds great promises in developing advanced electrocatalysts for energy storage.

A New Method of Gelatin Modified Collagen and Viscoelastic Study of Gelatin-Collagen Composite Hydrogel

Lang He,Sheng Li,Chengzhi Xu,Benmei Wei,Juntao Zhang,Yuling Xu,Beirong Zhu,Yang Cao,Xilin Wu,Zhijin Xiong,Rongrui Huang,Jian Yang,Haibo Wang 한국고분자학회 2020 Macromolecular Research Vol.28 No.9

Pure collagen materials are expensive with poor mechanical properties, which need modifications in most cases. As the degradation product of collagen, gelatin is cheap, degradable and biocompatible, but few literatures have reported the research about gelatin-collagen composite materials. This is because gelatin and collagen have different soluble temperatures—gelatin is soluble in hot water (≥30 oC) and swells in cold water. However, a low temperature (2-10 oC) is required to prepare and store collagen solution, and neutral collagen solution denatures quickly above the room temperature. In this study, gelatin was ground into powders and swelled in neutral bovine tendon pepsin-soluble collagen solution (BPSC) to form a homogeneous gelatin-collagen mixture, in light of the swelling characteristics of gelatin in cold water. The assembly properties and gel properties of this composite material were further studied. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) test results showed that the bovine tendon collagen had typical type-I collagen structural characterizations with two α chains of about 100 kDa and one β chain of about 200 kDa; while the SDS-PAGE pattern of gelatin displayed bands continuously distributed from 30 to 200 kDa. Amino acid composition analysis test indicated that the content of polar amino acids and the sum of acidic and base amino acids for gelatin were higher than that of BPSC. Studies on gel properties demonstrated that gelatin-collagen mixed solution had collagenlike assembly characteristics and assembly kinetics. The moduli of the assembled gel at 35 oC were equivalent to that of pure bovine tendon collagen system; moreover, the system moduli didn’t change with time with elastic moduli (G') of about 40 Pa. However, at 25 oC, the moduli of gelatin-collagen composite hydrogel increased with the extension of time, its G' increased about 18 times within 8 h, and the ratio of elastic modulus to viscous modulus (G'') increased 4.6 times, showing a significant aging effect of structural strength. Meanwhile, the mechanical strength of the composite hydrogel was also regulated by temperature—the gel was highly elastic (G'≈3,000 Pa, G'>>G'') at a low temperature (5 oC); as the temperature rose, the system moduli gradually decreased and the elastic gel transformed into waterlike fluid at 50 oC little by little. What’s more, gelatin-collagen composite hydrogel also had reversible sol-gel performances and self-healing capability similar to the gelatin hydrogel. This novel preparation method for preparing composite materials and the resultant composite hydrogel are expected to be used in the fields of natural food gels, injectable hydrogels, cell scaffolds, drug sustained-release materials and so on, and improve and promote the processing performances, price and large-scale production of collagen-based materials.

Hierarchical Model Predictive Control of Modular Multilevel Matrix Converter for Low Frequency AC Transmission

Lang Huang,Xu Yang,Bin Zhang,Liang Qiao,Hongchang Li,Mofan Tian 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

The modular multilevel matrix converter (M3C) applied to a low frequency alternating current (LFAC) transmission system is investigated. Due to the complexity and tight coupling of the converter, a novel hierarchical model predictive control (MPC) scheme with a cascaded structure of power control, capacitor voltage averaging and balancing control for M3C is proposed. The terminal behavioral model of M3C is derived out and the fast separated space-vectors approximation method is realized. The proposed scheme clearly achieves the system-level multi-objective control without the empirical procedure of the weighting factor design and significantly reduces the computational cost. This is the first time to apply the MPC to a converter in a hierarchical structure. Simulation results of a 7-level M3C are provided to illustrate the system’s performance.

Anthropogenic Climate Change

lang G. Bryden,Peter K. J. Robertson,Detlef W. Bahnemann 한국에너지기후변화학회 2006 에너지기후변화학회지 Vol.1 No.1

Der arge Weg der Erkenntnis : Zur Analysedes "Goya"-Romans von Lion Feuchtwanger auf dem Hintergrund seiner Biographie 리온 포이히트봥어의 생애를 배경으로 한 소설 "고야(Goya)"의 분석

Lange, Dietmar 단국대학교 1986 論文集 Vol.20 No.-

한국에는 리온 포이히트봥어(Lion Feuchtwanger)의 작품들이 아직 잘 알려져 있지 않는 편이다. 이 논문에서 논의된 그의 소설 「고야 또는 인식의 험난한 길」은 그의 전형적인 역사소설일 뿐만 아니라 그의 자서전적 요소들이 많이 내포되어 있으므로 제한된 범위에서나마 그의 인간과 작품을 이해하는 데 도움이 될 것이다. 뮨헨 출신의 유태인인 포이히트봥어는 일찍부터 연극 및 문예 비평과 더불어 희곡과 소설들을 쓰기 시작했다. 그러나 뮨헨의 떠돌이 문인에서 시작하여 독일 망명문학을 대표하는 세계적인 작가가 된다는 것은 멀고도 힘든 길이다. 포이히트봥어의 작품들 중에서는 역시 역사소설들이 큰 비중을 차지한다고 말할 수 있을 것이다. 이 논문에서 논의되고 있는 포이히트봥어의 소설 「고야 또는 인식의 험난한 길」의 주인공 고야(Goya)는 하층 사회에서 태어나 스페인의 가장 이름난 화가가 된 사람이다. 그러나 포이히트봥어의 소설에서는 고야가 궁정화가로서 이미 큰 성공을 거둔 이후의 그의 내면세계가 그려져 있다. 고야는 본의 아니게 정치에 말려들어 까이에따나 데 알바 공작부인과의 사랑과 증오의 감정이 뒤섞인 관계로 고통을 당하게 되고, 사랑하는 딸을 잃게 되고, 종교재판의 위협을 받게 되는 등 온갖 정신적 좌절을 경험하게 될 뿐만 아니라 청력까지 잃게 된다. 하지만 이 모든 어려움과 싸우는 동안 그의 시력은 더욱 날카로와져 그 시대를 풍미하던 의고전주의를 극복함으로써 인간의 본질을 꿰뚫어 보고 그것을 그릴 수 있게 된다. 고야는 그의 <관념들>을 형상화함으로써 스페인의 중세적 상황을 비유적으로 그릴 수 있었고, 그 결과 그의 그림을 보는 사람은 그러한 중세적 상황의 사악함과 그 극복의 필요성을 인식할 수 있게 되는 것이다. 왜냐하면 그의 그림에 나타난 <관념들>은 누가나 이해할 수 있는 世界語이기 때문이다. 소설「고야 」는 발전소설이다. 그러나 그 주인공은 직선적으로 발전하거나 이상적인 인간으로 승화되는 것이 아니라 내면적인 발전을 거듭하면서도 끝까지 모순투성이의 인간으로 남는다. 이 소설은 주인공의 내면적 갈등과 18세기 말 스페인의 절망적인 사회상을 强弱格(Trocha¨us)의 反語的인 사용과 視角 및 場面들의 다양한 변화를 통하여 생생하게 그리고 있다는 점에서 전형적인 20세기 유럽 소설이라고 할 수 있을 것이다. 무엇보다도 소설의 주인공이 사회적인 문제들에 말려들게 되고, 이에 대한 내면적 성향 과정을 통하여 예술적으로 완숙한 경지에 이른다는 것은 1차대전 이후에 씌어진 소설들의 공동광장(Topos)의 하나이기 때문이다. 그런 의미에서 이 소설의 주인공이 걷는 길은 망명작가 포이히트봥어 자신이 걸어간 길이었다. 또한〈이성을 위하여--우매와 폭력을 반대하여〉라는 포이히트봥어 작품들의 주도동기(Leitmotiv)가 이 소설에서 만큼 선명하게 부각된 곳은 없을 것이다.