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2021 ◽  
Vol 34 (1) ◽  
pp. 39
Author(s):  
Iwan Hermawan

The high demand for various plantation commodities in the world market, especially sugar, encourages the construction and operation of railroad lines in the Cirebon region. The construction and operation of railroad lines in Cirebon are directed to facilitate commodity traffic to be sent through the Port of Cirebon. The problem raised in this paper is related to what archeological remains are markers of the existence of the Cirebon-Cirebon Port Railway. The method used to answer these problems is the descriptive analysis method. Data collection was carried out through literature study and field observations. Dutch colonial railroad relics on the track in the form of the railbed, signal pole structure, boundary stakes, bridge structure, level crossing pole structure, and rail rods that are still installed. The existence of the railroad remains is a proof of the activities of the train transportation mode to the Port of Cirebon. Tingginya permintaan berbagai komoditas perkebunan di pasaran dunia, terutama gula mendorong dibangun dan dioperasikannya jalur kereta api di wilayah Cirebon. Pembangunan dan pengoperasian jalur kereta api di Cirebon diarahkan untuk memperlancar lalu lintas komoditas yang akan dikirim melalui Pelabuhan Cirebon. Salah satu bagian dari jalur kereta api yang dibangun, adalah jalur Stasiun cirebon - Pelabuhan Cirebon. Permasalahan yang diangkat pada tulisan ini, adalah berkenaan dengan tinggalan arkeologi apa saja yang menjadi penanda keberadaan Jalur kereta api Cirebon - Pelabuhan Cirebon. Metode yang dipergunakan untuk menjawab permasalahan tersebut, adalah Metode deskriptif analisis. Pengumpulan data dilakukan melalui studi Pustaka, dan pengamatan lapangan. Saat ini, Jalur kereta Cirebon - Pelabuhan merupakan jalur tidak aktif di wilayah Cirebon. Tinggalan perkeretaapian masa Kolonial belanda di jalur tersebut berupa railbed, struktur tiang sinyal, patok batas, patok KM, struktur jembatan, struktur tiang perlintasan sebidang, dan batang rel yang masih terpasang. Keberadaan tinggalan perkeretaapian tersebut merupakan bukti aktifitas moda angkutan kereta api menuju Pelabuhan Cirebon.


2020 ◽  
Vol 69 (1) ◽  
Author(s):  
Jie Zhang ◽  
Mao Ueda ◽  
Sophie Campen ◽  
Hugh Spikes

AbstractThe frictional properties of ZDDP tribofilms at low entrainment speeds in boundary lubrication conditions have been studied in both rolling/sliding and pure sliding contacts. It has been found that the boundary friction coefficients of these tribofilms depend on the alkyl structure of the ZDDPs. For primary ZDDPs, those with linear alkyl chains give lower friction those with branched alkyl chain ZDDPs, and a cyclohexylmethyl-based ZDDP gives markedly higher friction than non-cyclic ones. Depending on alkyl structure, boundary friction coefficient in rolling-sliding conditions can range from 0.09 to 0.14. These differences persist over long duration tests lasting up to 120 h. For secondary ZDDPs, boundary friction appears to depend less strongly on alkyl structure and in rolling-sliding conditions stabilises at ca 0.115 for the three ZDDPs studied. Experiments in which the ZDDP-containing lubricant is changed after tribofilm formation by a different ZDDP solution or a base oil indicate that the characteristic friction of the initial ZDDP tribofilm is lost almost as soon as rubbing commences in the new lubricant. The boundary friction rapidly stabilises at the characteristic boundary friction of the replacement ZDDP, or in the case of base oil, a value of ca 0.115 which is believed to represent the shear strength of the bare polyphosphate surface. The single exception is when a solution containing a cyclohexylethyl-based ZDDP is replaced by base oil, where the boundary friction coefficient remains at the high value characteristic of this ZDDP despite the fact that rubbing in base oil removes about 20 nm of the tribofilm. XPS analysis of the residual tribofilm reveals that this originates from presence of a considerable proportion of C-O bonds at the exposed tribofilm surface, indicating that not all of the alkoxy groups are lost from the polyphosphate during tribofilm formation. Very slow speed rubbing tests at low temperature show that the ZDDP solutions give boundary friction values that vary with alkyl group structure in a similar fashion to rolling-sliding MTM tests. These variations in friction occur immediately on rubbing, before any measurable tribofilm can develop. This study suggest that ZDDPs control boundary friction by adsorbing on rubbing steel or tribofilm surfaces in a fashion similar to organic friction modifiers. However it is believed that, for primary ZDDPs, residual alkoxy groups still chemically bonded to the phosphorus atoms of newly-formed polyphosphate/phosphate tribofilm may also contribute to boundary friction. This understanding will contribute to the design of low friction, fuel efficient crankcase engine oils. Graphical Abstract


2020 ◽  
pp. 152808372097891
Author(s):  
Suguru Ando ◽  
Masayuki Kaneda ◽  
Kazuhiko Suga

The D3Q27 lattice Boltzmann method (LBM) combined with the fluid-structure boundary reconstruction (fsBR) scheme and the interpolated bounce back (IPBB) method is extensively evaluated to predict the permeability of nonwoven fibrous porous media. The fsBR-IPBB method transfers digitally defined step-like boundary data, e.g. the three-dimensional structure data obtained by the X-ray computed tomography, to continuous smooth boundary data via level-set functions. It leads to highly accurate calculations despite low lattice resolutions of thin fibers with circular cross-sectional shapes, compared to the conventional half-way bounce back (HWBB) method. The fsBR-IPBB method is first applied to predict the permeability of two different arrays of impermeable circular cylinders and verified by comparing the results with the data in the literature. We then validate the method referring to the numerically and experimentally obtained permeability of six types of nonwoven fabrics prepared by the industrial hydroentanglement process. Finally, the discussion on the applicability and the limitation of the macroscopic correlation models to estimate permeability of porous media is carried out. The results show that although the calculated permeability is in reasonable agreement with the measured one with an error of 8.1–16.3%, analytical or empirical correlation models fail to give the correct trend due to the highly inhomogeneous and anisotropic properties of hydroentangled nonwoven fabrics.


2020 ◽  
Vol 34 (34) ◽  
pp. 2050389 ◽  
Author(s):  
Xin-Yi Gao ◽  
Yong-Jiang Guo ◽  
Wen-Rui Shan

The Burgers-type equations are applied to oceanography, hydrodynamic turbulence, gas dynamics, shock-wave formation, acoustic transmission structure, boundary-layer behavior, continuum-traffic simulation, convection-dominated diffusion, wave formation in the thermo-elastic media, vorticity transport, dispersion in the porous media, particle sedimentation in fluid suspension, colloid evolution, and so forth. Hereby, taking into account the wave processes in hydrodynamics and acoustics, we investigate an extended coupled (2+1)-dimensional Burgers system, and with symbolic computation, work out a scaling transformation, two hetero-Bäcklund transformations and two auto-Bäcklund transformations, with the soliton solutions. Our results are dependent on the coefficients in the system.


2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Ruichao Lian ◽  
Shikai Jing ◽  
Zefang Shi ◽  
Zhijun He ◽  
Guohua Song

In the structural topology optimization approaches, the Moving Morphable Component (MMC) is a new method to obtain the optimized structural topologies by optimizing shapes, sizes, and locations of components. However, the optimized structure boundary usually generates local nonsmooth areas due to incomplete connection between components. In the present paper, a topology optimization approach considering nonsmooth structural boundaries in the intersection areas of the components based on the MMC is proposed. The variability of components’ shape can be obtained by constructing the topology description function (TDF) with multiple thickness and length variables. The shape of components can be modified according to the structural responses during the optimization process, and the relatively smooth structural boundaries are generated in the intersection areas of the components. To reduce the impact of the initial layout on the rate of convergence, this method is implemented in a hierarchical variable calling strategy. Compared with the original MMC method, the advantage of the proposed approach is that the smoothness of the structural boundaries can be effectively improved and the geometric modeling ability can be enhanced in a concise way. The effectiveness of the proposed method is demonstrated for topology optimization of the minimum compliance problem and compliant mechanisms.


Author(s):  
Stephan Priebe ◽  
Daniel Wilkin ◽  
Andy Breeze-Stringfellow ◽  
Giridhar Jothiprasad ◽  
Lawrence C. Cheung

Abstract Shock/boundary layer interactions (SBLI) are a fundamental fluid mechanics problem relevant in a wide range of applications including transonic rotors in turbomachinery. This paper uses wall-resolved large eddy simulation (LES) to examine the interaction of normal shocks with laminar and turbulent inflow boundary layers in transonic flow. The calculations were performed using GENESIS, a high-order, unstructured LES solver. The geometry created for this study is a transonic passage with a convergent-divergent nozzle that expands the flow to the desired Mach number upstream of the shock and then introduces constant radius curvature to simulate local airfoil camber. The Mach numbers in the divergent section of the transonic passage simulate single stage commercial fan blades. The results predicted with the LES calculations show significant differences between laminar and turbulent SBLI in terms of shock structure, boundary layer separation and transition, and aerodynamic losses. For laminar flow into the shock, significant flow separation and low-frequency unsteadiness occur, while for turbulent flow into the shock, both the boundary layer loss and the low-frequency unsteadiness are reduced.


The millennial era of the 21st century has fallen witness to the emergence of popular artistic works that transcend beyond reality marks and serve as a condition of the hyper-reality world. In this context, this paper work argues that Malay theatre performance is a popular art form that has risen and built its own tendency as a post-modern art product that violates the realism structure boundary and acts as a hyper-reality world. This must have been caused by the Malay theatre direction that comes with recent directors who have the desire to violate this realism structure, in their assertion of new theatre performance forms. Related to this, our current paper work discusses the work directed by Namron entitled ‘Lembu’ and another one by Wan Khairunazwan Rodzy entitled ‘Tepuk Amai-Amai’ that have olated the boundary of the realism structure by forming themselves as hyper reality theatre. Using the non-structured observation method and the application of the hyper semiotics theory as the study’s analysis outcome, this paper is able to explain the form of hyper reality theatre created by both directors as their effort to oppose to the realism theatre style in Malay theatre performance. This article’s main discussion is based on the interpretation of the actors’ acting form sign-system, the stage scenic sign-system, the stage lighting composition signsystem and the characters’ costume sign-system that have been channelled to both theatres ‘Lembu’ and ‘Tepuk Amai-Amai’. Thus, the findings in this article show that the actors’ acting form sign-system, the stage scenic sign-system, the stage lighting composition sign-system and the characters’ costume sign-system in ‘Lembu’ and ‘Tepuk Amai-Amai’ are the conditions of the proper sign, pseudo sign, false sign, recycle sign and superlative sign that mix together in the performance space. Thus, the integration among the proper sign, pseudo sign, false sign, recycle sign and superlative sign which overlap has led to this newly formed theatrical performance of Lembu and Tepuk AmaiAmai as hyper reality theatre and given a hyper-reality world experience into the staging Malay theatre today


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