scholarly journals Market Transportasi UK: Regulasi atau Kompetisi

2021 ◽  
Author(s):  
AMIRUDDIN AKBAR FISU
Keyword(s):  

Tulisan ini merupakan ulasan market transportasi publik yang terjadi di Inggris terutama angkutan bus dan kereta api. Pada bagian awal membahas tentang mekanisme pasar layanan transportasi bus, kemudian bagaimana efek dari deregulasi yang dilakukan pada tahun 1990, serta bagaimana masalah dari deregulasi tersebut. Deregulasi berdampak pada ketidakstabilan pasar, pengaruhnya terhadap service atau layanan, kebijakan subsidi dan persaingan pada rute-rute yang disubsidi, alternative operator, hingga establishing demand pattern dan keinginan penumpang.

Author(s):  
Jung-Hoon Cho ◽  
Seung Woo Ham ◽  
Dong-Kyu Kim

With the growth of the bike-sharing system, the problem of demand forecasting has become important to the bike-sharing system. This study aims to develop a novel prediction model that enhances the accuracy of the peak hourly demand. A spatiotemporal graph convolutional network (STGCN) is constructed to consider both the spatial and temporal features. One of the model’s essential steps is determining the main component of the adjacency matrix and the node feature matrix. To achieve this, 131 days of data from the bike-sharing system in Seoul are used and experiments conducted on the models with various adjacency matrices and node feature matrices, including public transit usage. The results indicate that the STGCN models reflecting the previous demand pattern to the adjacency matrix show outstanding performance in predicting demand compared with the other models. The results also show that the model that includes bus boarding and alighting records is more accurate than the model that contains subway records, inferring that buses have a greater connection to bike-sharing than the subway. The proposed STGCN with public transit data contributes to the alleviation of unmet demand by enhancing the accuracy in predicting peak demand.


2020 ◽  
Vol 21 (1) ◽  
pp. 1
Author(s):  
D.I Ansusa Putra

<p><em>Dajjal appearance discussion in the last decade has been the trending among Muslim. There are massive search for religious doctrines text on Dajjal in digital media. This is oriented towards certain views about the world, social and cultural conditions, political project, political subjectivity, attitudes, and practice or competence. The behavior affects social-political life through the contextualization of hadith about Dajjal. This study aims to obtain a complete picture of digital media behavior in understanding religious doctrines related to  Fitna of Dajjal among Muslims. This article combines Muslim theory of Cosmopolitanism Khairuddin Aljunied and living hadith approach, supported by data from google trend search throughout 2019. The results showed that there were four digital behaviors of Indonesian Muslim related to Dajjal hadith, first, searching instantaneously; second, reviewing from internet; third, joining the contextualisation discussion; and fourth, liking the personalization and illustration. The most frequently sought topic is about the prayer to be protected from Fitna of Dajjal. In addition, the study also tried to prove that this digital behavior is formed massively because of supply and demand pattern. It means that there are groups producing Dajjal hadith in public sphere regularly since they are supported by the many interests of consumers.</em></p>


2017 ◽  
Vol 46 ◽  
pp. 618-630 ◽  
Author(s):  
Luis A. San-José ◽  
Joaquín Sicilia ◽  
Manuel González-De-la-Rosa ◽  
Jaime Febles-Acosta

2009 ◽  
Vol 122 (2) ◽  
pp. 519-524 ◽  
Author(s):  
Beatriz Abdul-Jalbar ◽  
José M. Gutiérrez ◽  
Joaquín Sicilia

2011 ◽  
Vol 487 ◽  
pp. 526-532 ◽  
Author(s):  
Zhi Hong Li ◽  
B. Zhao ◽  
Liang Li ◽  
J. Wong

China becomes the biggest producing country of synthetic diamond in the world. China’s output in 2010 is in excess of 7 billion carats. The yearly average increase rate is nearly 20% for the last 10 years. It almost accounts for 90% of the world’s production. China’s diamond is exported to 58 countries and regions in 2009. The yearly average export increase rate is about 30% for the last 10 years. Two main reasons supported such growth: 1) Continuous improvements made to the diamond synthesizing technology and as a result quality becoming better and better and to a large extend Chinese diamond is close to or equal to those made by her Western counterparts in terms of quality. 2) Competitive prices. The average price is only about $0.05 per carat in 2009, making it irresistible for world users to turn to Chinese diamond. Diamond producers in the Western countries turn to produce more profitable products like PCD & PCBN. This paper delivers some key statistics of Chinese diamond output and export in the last 10 years; it also highlights the diamond import in USA and Japan. The USA is the biggest consumer of China’s diamond. The supply & demand pattern for synthetic diamond is very much different from what it used to be 10 years ago. All these facts are further illustrated by the 10 figures and 1 table in this paper.


2008 ◽  
Vol 1 (1) ◽  
pp. 27-38 ◽  
Author(s):  
E. J. M. Blokker ◽  
J. H. G. Vreeburg ◽  
S. G. Buchberger ◽  
J. C. van Dijk

Abstract. Today, there is a growing interest in network water quality modelling. The water quality issues of interest relate to both dissolved and particulate substances. For dissolved substances the main interest is in residual chlorine and (microbiological) contaminant propagation; for particulate substances it is in sediment leading to discolouration. There is a strong influence of flows and velocities on transport, mixing, production and decay of these substances in the network. This imposes a different approach to demand modelling which is reviewed in this article. For the large diameter lines that comprise the transport portion of a typical municipal pipe system, a skeletonised network model with a top-down approach of demand pattern allocation, a hydraulic time step of 1 h, and a pure advection-reaction water quality model will usually suffice. For the smaller diameter lines that comprise the distribution portion of a municipal pipe system, an all-pipes network model with a bottom-up approach of demand pattern allocation, a hydraulic time step of 1 min or less, and a water quality model that considers dispersion and transients may be needed. Demand models that provide stochastic residential demands per individual home and on a one-second time scale are available. A stochastic demands based network water quality model needs to be developed and validated with field measurements. Such a model will be probabilistic in nature and will offer a new perspective for assessing water quality in the drinking water distribution system.


2020 ◽  
pp. 17-26
Author(s):  
Gustavo Meirelles ◽  
◽  
Aloysio Saliba ◽  
Jorge Tarqui ◽  
Edna Viana ◽  
...  

Neste trabalho são avaliados os transitórios hidráulicos decorrentes da operação otimizada de uma estação elevatória de uma rede de distribuição de água e os procedimentos operacionais que podem reduzir este problema para assegurar a confiabilidade do sistema. A operação otimizada é obtida utilizando o algoritmo Particle Swarm Optimization (PSO) e simulações em regime permanente, considerando que as bombas estarão operando com sua velocidade de rotação nominal ou desligadas. Em seguida, as manobras de arranque e paragem definidas são utilizadas num modelo em regime transitório para avaliar as variações de pressão decorrentes da operação otimizada. Os resultados obtidos demonstram que as variações de pressão não são elevadas, mas que, a longo prazo, podem ser significativos na redução da vida útil dos equipamentos hidráulicos. Além disso, observou-se que a variação da demanda num modelo transitório pode causar erros significativos, sendo necessária uma modelação cautelosa neste aspeto. In this work, the hydraulic transients resulting from the optimized operation of a pumping station in a water distribution network are studied and operational procedures to reduce this problem and ensure the reliability of the system are evaluated. An optimal pumping scheduling is obtained using the Particle Swarm Optimization (PSO) and a steady state model considering pumps operating only at their nominal rotational speed or switched off. Then, the pumps schedules are used in a transient model to evaluate the pressure surges of the optimized operation. The results showed that the pressure variation is not high but can be relevant in the reduction of service life of the hydraulic equipment. In addition, it was observed that the demand pattern in the transient model can cause significant errors, and its modeling has to be carefully handled.


2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Oluwafemi Ajayi ◽  
Reolyn Heymann

Purpose Energy management is critical to data centres (DCs) majorly because they are high energy-consuming facilities and demand for their services continue to rise due to rapidly increasing global demand for cloud services and other technological services. This projected sectoral growth is expected to translate into increased energy demand from the sector, which is already considered a major energy consumer unless innovative steps are used to drive effective energy management systems. The purpose of this study is to provide insights into the expected energy demand of the DC and the impact each measured parameter has on the building's energy demand profile. This serves as a basis for the design of an effective energy management system. Design/methodology/approach This study proposes novel tunicate swarm algorithm (TSA) for training an artificial neural network model used for predicting the energy demand of a DC. The objective is to find the optimal weights and biases of the model while avoiding commonly faced challenges when using the backpropagation algorithm. The model implementation is based on historical energy consumption data of an anonymous DC operator in Cape Town, South Africa. The data set provided consists of variables such as ambient temperature, ambient relative humidity, chiller output temperature and computer room air conditioning air supply temperature, which serve as inputs to the neural network that is designed to predict the DC’s hourly energy consumption for July 2020. Upon preprocessing of the data set, total sample number for each represented variable was 464. The 80:20 splitting ratio was used to divide the data set into training and testing set respectively, making 452 samples for the training set and 112 samples for the testing set. A weights-based approach has also been used to analyze the relative impact of the model’s input parameters on the DC’s energy demand pattern. Findings The performance of the proposed model has been compared with those of neural network models trained using state of the art algorithms such as moth flame optimization, whale optimization algorithm and ant lion optimizer. From analysis, it was found that the proposed TSA outperformed the other methods in training the model based on their mean squared error, root mean squared error, mean absolute error, mean absolute percentage error and prediction accuracy. Analyzing the relative percentage contribution of the model's input parameters based on the weights of the neural network also shows that the ambient temperature of the DC has the highest impact on the building’s energy demand pattern. Research limitations/implications The proposed novel model can be applied to solving other complex engineering problems such as regression and classification. The methodology for optimizing the multi-layered perceptron neural network can also be further applied to other forms of neural networks for improved performance. Practical implications Based on the forecasted energy demand of the DC and an understanding of how the input parameters impact the building's energy demand pattern, neural networks can be deployed to optimize the cooling systems of the DC for reduced energy cost. Originality/value The use of TSA for optimizing the weights and biases of a neural network is a novel study. The application context of this study which is DCs is quite untapped in the literature, leaving many gaps for further research. The proposed prediction model can be further applied to other regression tasks and classification tasks. Another contribution of this study is the analysis of the neural network's input parameters, which provides insight into the level to which each parameter influences the DC’s energy demand profile.


2020 ◽  
Vol 12 ◽  
pp. 184797902094148
Author(s):  
Zhiyi Zhuo ◽  
Ka Yin Chau ◽  
Shizheng Huang ◽  
Yun Kit Ip

Customer demand is the core of the vendor’s implementation of product supply strategies. There are three different patterns of demand: real demand, false demand, and semi-real demand. For this article, we study the product supply strategy formulated for manufacturer-to-group customers based on a semi-real demand pattern. Firstly, we construct two mathematical models in which the manufacturer obtains the best profit based on the two supply modes in the semi-real demand pattern. Secondly, we solve the optimal production volume and optimal pricing. Finally, numerical examples are used to verify the validity of the model. In accordance with the optimization principle, results of the analysis are extended to the range of optimal value of product profit in the demand model, so as to explore the mechanism of manufacturers for maximizing group customers’ product profits under the semi-real demand model.


Sign in / Sign up

Export Citation Format

Share Document