2,298 research outputs found
Author\u27s Response to In My World: Designing Living & Learning Environments for the Young Creating Children’s Environments that Inspire and Instruct by Ro Logrippo
No full textAuthor\u27s Response to In My World: Designing Living & Learning Environments for the Young: Creating Children’s Environments that Inspire and Instruct by Ro Logripp
Ro-Ro verbinding Vuurland met het vasteland van Argentinië
No full textIn het vooronderzoek is voorbereidend werk gedaan voor het ontwerp van de Ro-Ro-haven. In het voor u liggende rapport staat beschreven hoe dit ontwerp verder is uitgewerkt. In het eerste hoofdstuk wordt een inventarisatie gemaakt welk type schip er voor dit specifieke Ro-Ro-vervoer ingezet moet worden. Na de te vervoeren lading in hoofdstuk 3 te hebben besproken wordt de indeling van het schip vastgesteld. Deze indeling moet zodanig zijn dat het aan te vereiste vervoerskapaciteit voldoet. In de daarop volgende hoofdstukken wordt het programma van eisen op nautisch gebied behandeld. Hier komen onderwerpen ter sprake zoals de breedte en vorm van de haventoegang. Binnen de haven zijn korrektie- en stopafstand en de afmetingen van de draaicirkel van groot belang voor de manoeuvreerbaarheid van de schepen. Het enorme getijverschil heeft grote invloed op het havenontwerp. Er is daarom in hoofdstuk 7 een mathematisch model van de getijkromme gemaakt waarmee een voorspelling van de waterstanden kan worden gedaan. Dit is o.a. van nut geweest bij de bepaling van de ligging van de brekerzone en de probabilistische benadering van de noodzakelijke geuldiepte. De golfbrekers moeten de haven bescherming bieden tegen golfaanval vanuit zee. Daarom is aan dit belangrijk element in het projekt veel aandacht besteed. Een interessant aspekt hierbij is ook de bepaling van de kruinhoogte. Het P.I.A.N.C. heeft strenge eisen gesteld aan de golfdoordringing bij Ro-Ro-havens i.v.m. de gevoeligheid van de lading voor bewegingen van het schip. Uitgaande van deze eisen is een diffraktieberekening gemaakt om te onderzoeken in hoeverre het ontwerp voldoet aan de P.I.A.N.C. eisen. Om een goede ladingafhandeling mogelijk te maken is een flexibele pontonkonstruktie ontworpen die bij elke getijwaterstand kan funktioneren. Daar de ponton geen stootbelasting kan opnemen is tussen schip en ponton een remmingwerk gesitueerd. Dit is berekend op een extreme stootbelasting van het Ro-Ro-schip. Tenslotte is een berekening gemaakt van de troskrachten die optreden bij windbelasting op het schip als het ligt afgemeerd.Hydraulic EngineeringCivil Engineering and Geoscience
Development overview of Ro-Ro ships
No full textRazvoj Ro-Ro brodova traje u kontinuitetu već više od 180 godina. Svoj povijesni razvoj započinje u Škotskoj gdje se pojavio prvi trajekt koji prevozi Ro-Ro teret, u ovom slučaju željezničke vagone. Ro-Ro brodovi razvijaju se usporedno s integralnim i multimodalnim prijevozom jer su i oni sami dio ovog tipa transporta. U 60-im godinama prošlog stoljeća dolazi do uspostavljanja velikog broja kratkih linija na području Sjevernog i Baltičkog mora, koje se danas nastoji ponovno oživjeti. Prednosti Ro-Ro brodova u početku su bile vidljive na kraćim relacijama no naknadno ih pokazuju i dugim relacijama. Najniža visina troškova po jedinici tereta u usporedbi sa drugim sustavima kao prvenstvena prednost Ro-Ro tehnologije omogućena je dobrim prekrcajnim normama te se danas uspješno kombinira sa drugim tehnologijama. Isključiva namjena Ro-Ro brodova je prijevoz tereta na kotačima. U uvodnom dijelu rada autor analizira i interpretira te opisuje razvoj Ro-Ro brodova kroz pojedina povijesna razdoblja, a zatim opisuje suvremeni Ro-Ro brod i njegove osnovne karakteristike. U drugom dijelu rada autor provodi analizu prometa Ro-Ro brodova na Jadranu u posljednjih 5 godina. Vezano uz to autor nudi pojedine zaključke i prijedloge. U posljednjem dijelu rada (Zaključak) dana su zaključna razmatranja o temi.The development of Ro-Ro ships has been going on continuously for more than 180 years. Its historical development begun in Scotland where the first ferry carrying Ro-Ro cargo is primarily applied, and in this case railway wagons. Ro-Ro ships are being developed parallel with integrated and multimodal transport because they themselves are part of this type of transportation. In the 1960s, a large number of short lines were established in the North and Baltic Seas, which are now being revived. The advantages of Ro-Ro boats were initially visible on shorter distances, but later they also showed them on long distances. The lowest cost per unit of cargo compared to other systems as a primary advantage of ro - ro technology is provided by good transhipment standards and today is successfully combined with other technologies. The exclusive purpose of Ro-Ro boats is to transport cargo on wheels. In the introductory part of the paper, the author analyzes and interprets and describes the development of Ro-Ro boats through certain historical periods, and then describes the modern Ro-Ro ship and its basic characteristics. In the second part of the paper, the author analyzes the traffic of Ro-Ro boats in the Adriatic sea in the last 5 years. In this regard, the author offers some conclusions and suggestions.
In the last part of the paper (Conclusion), concluding remarks on the topic are given
Direct numerical simulation of weakly spanwise-rotating turbulent plane Couette flow
No full textIn this report, we conduct direct numerical simulations (DNS) of weakly spanwise-rotating plane Couette flows at Reynolds number (here, is the half the wall velocity difference, and is half-channel height). A series of simulations with different rotation numbers ( is constant angular velocity component in the spanwise direction) is carried out to investigate the effect of on the flow statistics. Our results show that the flow statistics are affected by the , and a "critical" rotation number (between and ) is observed, where the kinetic energy of secondary flow contributes about a half of the turbulent kinetic energy, and the mean shear rate at the center line reaches a minimum value. We conjecture that different mechanisms should exist around , and will be investigated further
Development of an Auto-Trim Control System for Ro-Ro Ship Carrying Heavy Cargoes
No full textIn Ro-Ro ship carrying heavy cargoes, it is very important to maintain a certain level of aft draft and the proper trim through the entire loading or discharging process. Some kinds of manual ballast control system have been generally applied so far to this practice in Ro-Ro ship. However, there is need to develop a so-called Auto-Trim Control System using some computer technology to improve the operation of those existing systems.
This paper aims at developing an Auto-Trim Control System especially for Ro-Ro ship carrying such heavy cargoes including hot coils and steel plates. The author carried out some systems analysis and design for developing the system by examining and reflecting the practices of the entire loading and discharging process.
Then a user-friendly Auto-Trim Control System has been built by interfacing the Valve Remote Control system and Tank Level & Draft Measuring system with itself. The author also provides some excellent results on the performance of the system by reporting the records of installing the system on board 4 Ro-Ro ships.Abstract
제 1 장 서론 = 1
1.1 연구의 배경 = 1
1.2 연구의 목적 = 2
제 2 장 시스템의 개요 = 3
2.1 중량화물 선적 Ro-Ro 선 하역 작업의 기본개념 = 3
2.2 Auto-Trim Control System의 기본개념 = 7
2.3 시스템 구성도 = 10
제 3 장 선미흘수 및 트림 제어 알고리듬의 개발 = 11
3.1 탱크 배치도 = 11
3.2 탱크 배정 우선순위 = 11
3.3 탱크 선택 규칙 = 12
제 4 장 Auto-trim Control System 개발 = 15
4.1 시스템 소프트웨어 구성 = 15
4.2 시스템 설계 = 16
4.3 밸브 및 펌프 작동 절차 = 21
4.4 시스템 구현 = 37
제 5 장 프로그램 실행 예 = 42
5.1 통신상태 표시줄 = 42
5.2 선박상태 표시줄 = 44
5.3 프로그램 작동 = 45
제 6 장 결론 = 58
참고문헌 = 6
High silica concentration in RO concentrate
No full textSilica scaling is one of the major scaling challenges in Reverse Osmosis (RO). The safe operation practice is to keep the silica concentration below 150 mg/L in RO concentrate. This study addresses the effects of divalent cations such as calcium and magnesium on silica scaling in a seawater RO installation used as a pretreatment to Eutectic Freeze Crystallisation (EFC). Results showed that in the absence of antiscalant and divalent cations a sustained silica concentration of approximately 280 mg/L in concentrate is possible without declining membrane permeability. At a higher concentration of divalent cations, the membrane permeability decreased. Membrane autopsy and analysing destructed membrane showed a relatively low magnesium and a high calcium concentration on the membrane after adding divalent ions into the solutions. It is concluded that in absence of divalent cations and without antiscalant the limits of 150 mg/L silica can be extended to 280 mg/L for 6–8 h.Sanitary Engineerin
Prediction performance of RO desalination plants
No full textThe present work will describe how a complete mixing model can be used to predict RO plant performance. Operating data for Manfouha RO plants were used to check on the validity of the values obtained from the proposed model. Good agreement was obtained. Discussions of the field data for Manfouha RO plant will be presented.Corresponding Author:
Prof. Ibrahim S. Al-Mutaz, Professor
Chemical Engineering Department, College of Engineering, King Saud University,
P.O. Box 800, Riyadh-11421, Saudi Arabia.
Email: [email protected]
Sadetpho ro. 5
No full textThe author presents her views that go against religious practices of the King Rama V cult's followers. Drawing on Buddhism and Hinduism, she criticizes that the offering of whisky to the King's portraits and calling the King Sadetpho ro. 5 are practices that ignore the royal dignity of King Rama V who was considered the great king of Thailand
PURO: A unique RO-design for brackish groundwater treatment
No full textDepletion of fresh groundwater sources as the result of overdraft, salinization and pollution becomes a major problem in parts of the world. Desalination of brackish groundwater by membrane technology, e.g. reverse osmosis (RO), seems to be a promising solution to water scarcity problems. However, energy consumption and concentrate disposal are considered as the main reasons for avoiding RO application. In order to overcome these drawbacks, the PURO concept, which consists of vertically-configured RO unit in an especially drilled well is designed, installed and is going to be tested. The installation operates without any chemical pretreatment and therefore, the concentrate can be injected into a deeper confined aquifer that contains water of similar concentration. To avoid chemical pretreatment, the system operates at lower recovery (50%) than conventional brackish groundwater reverse osmosis (BWRO). Higher energy consumption, as the results of lowering the recovery, is avoided by using natural hydrostatic pressure at the depth that RO is installed and by extracting the permeate water only. PURO consumes about 39% less energy when compared to a conventional BWRO installation of the same capacity. This article describes the PURO concept and discusses its advantages and disadvantages. It also provides a rough calculation of water cost for PURO and conventional BWRO with emphasizing on the energy costs.Sanitary Engineerin
High silica concentration in RO concentrate and Magnesiumsilica polymers formation
No full textScaling is a major barrier in increasing recovery of RO installations. One of the major unresolved scaling problems in RO is silica scaling. Depending on pH and temperature, the safe operation practice to prevent silica scaling is to keep silica concentration below 150 [mg/l] in the concentrate. In this study, it was investigated whether it is possible to gain the high recovery and the very high silica concentration by removing divalent ions from the feed water by using ion exchange column. A total recovery of 90% is achieved without using antiscalant and with constant flux. The results show that in absence of antiscalant and divalent ions, silica concentration of about 280 [mg/l] in concentrate is possible without declining of mass transfer through the membrane.Sanitary EngineeringWatermanagementCivil Engineering and Geoscience
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