ADVANCED METHODS OF BIOGAS PURIFICATION – A REVIEW

One of the main environmental problems of today’s society is the continuously increasing production of organic wastes. The discovery of abundant natural gas resources has greatly increased the study of using methane as a feed stock to produce transportation fuels. Biogas (primarily containing methane and carbon dioxide), which is generated from biomass or organic waste via anaerobic digestion or from landfills, is regarded as a renewable source of methane, and has the potential to achieve sustainable production of transportation fuels. Since biogas also contains a significant amount of impurities (e.g.,hydrogen sulphide, ammonia, water vapor and siloxane), a procedure is generally required to clean it before its final use.In this paper are presented the advanced methods of biogas purification

THE QUALITY OF GRADUATES, EMPLOYERS AND HIGHER EDUCATION

Education and research are important pillars of society based on knowledge, aiming the ensurance of personal development of every citizen, the prosperity of society and sustainable development. A priority in its framework should be the education for labour market under the conditions of ensuring equal opportunities. The finality of education for the labour market should be the preparation for the permanent participation in the national and European labour market, the education being a preventing poverty factor. The purpose of this paper is to determine the differences between "ideal quality" of the higher education system from the point of view of the main stakeholders, namely direct clients (graduates) and the actual quality appreciated by them based on their experience with the labour market. The research results highlight the existence of some gaps between the skills and abilities effectively developed and those that should be developed in accordance with the requirements of employers, in graduates’ opinion, formed on the basis of experience gained as employees or job applicants in the first year after graduation

Simulation of an Electro-hydraulic Circuit for ALARS

In this paper, the authors present hydraulic and electro-hydraulic simulations of the circuits needed for ALARS (Automated Launch and Recovery System). In fact, the ALARS is used to launch the side-scan sonar into the sea. First hydraulic circuit has the following devices: tank, filter, fixed displacement pump, check valve, 4/3- way valve with two buttons, throttle valve, pressure relief valve and hand lever valve, tanks reservoir, filter and double acting cylinder (Cy 1-1). Afterwards, second hydraulic circuit has the following devices: pump unit, 4/2-way hand lever valve, throttle valve and two double acting cylinders (Cy 2-1 and Cy 2-2). Forward, the first electro-hydraulic circuit has the following devices: lamp, valve solenoid, pressure relief valve, double acting cylinder (Cy 3-1), throttle valve, 4/2-way solenoid valve, fixed displacement pump, valve displacement pump and tanks. Ultimately, the second electro-hydraulic circuit has the following devices: tank, pump unit, pressure relief valve, double acting cylinders (Cy 4-1 and Cy 4-2), relay, valve solenoid, and lamp

The Use of Double-acting Cylinders in Electro-hydraulic Circuit

The paper presents aspects related use of double-acting cylinder. Besides, in the article are presented three hydraulic schemes that double acting cylinder. Meaning, two hydraulic circuits and one electro-hydraulic circuits. First hydraulic schemes has the following devices: fixed displacement pump, air filter, 4/3 way hand lever valve, tanks reservoir, filter and double acting cylinder (Cyli 1-1). However, second hydraulic scheme has the following devices: fixed displacement pump, 4/3 way hand lever valve, check valves, valve office and two double acting cylinders (Cyli 2-1 and Cyli 2-2). Forward, the electro-hydraulic circuit has the following devices: tanks, throttle check valves, 5/2 way hand lever valve, fixed displacement pump, lamp, relays, relay with switch-on delay, valve solenoid and double acting cylinder (Cyli 3-1). The design and simulation of the all three circuits from this article is done FluidSim software from Festo

Researches Regarding the Use of Non-conventional Actuators

The purpose of this article is to present relevant concepts about the study of electro-pneumatic circuits using fluidic muscle actuators. The fluidic muscle is a type of pneumatic actuator having an extensive history of technical applications in the biomechanical field since the 1955. After Introduction, the authors study two pneumatic circuits. In fact, the first pneumatic circuit in this paper has only one actuator (fluidic muscle 1-1), but the second pneumatic circuit has two actuators (fluidic muscles 2-1 and 2-2. Further on, the authors present two electro-pneumatic schematics, a simple electro-pneumatic circuit and another electro-pneumatic circuit with PLC (Programmable Logic Controller). This type of actuator is used in robotics, material handling, motion control, industrial field and other applications. The pneumatic and electro-pneumatic circuits given in this paper are made using FluidSim software from Festo. In this case, the fluidic muscles are only non-conventional actuators. However, in pneumatic installations as well as in electro-pneumatic installations, the non-conventional actuators have the following advantages: strength, compactness, reliability, low price, ease of assembly or disassembly from their circuits, etc. Of course, in practice are many types of fluidic muscles, which are used in electro-pneumatic installations

Control Efficiency Improvement of an Electro-hydraulic Winch

The paper presents a study regarding electro-hydraulic control systems for drive winches, a structural part of LARS (Launch and Recovery Systems). In the Introduction section of the paper, the authors present the domains of the research vessel. Furthermore, there is presented the importance of launch and recovery systems (LARS) and drive winches on the deck of a research vessel. The launch and recovery systems (LARS) using drive winches are installed on the stern of the research vessel. Further in the paper, the authors present the results of studying three simplified systems that use electric, hydraulic and electro-hydraulic driving solutions. Furthermore, there are presented comparative advantages of using this three types of drive winches. At the end of the paper, the authors perform an analysis of the electro-hydraulic systems for the drive winch, using a modelling and simulation software. Each schematic is presented along with its components. Moreover, the authors mention that all the schematics presented in this paper are modelled using FluidSim software from FESTO. In this case, only three mathematic relations are used in the paper: the Cauchy momentum (convective form), the incompressible Euler relations and the pressure losses in the hydraulic and electro-hydraulic drive winch