Sound processing with loudspeaker driving depends critically on high quality electroacoustic transducers together with their relevant amplifiers. In this paper, the nonlinear effects of electrodynamic loudspeakers are investigated as regard the influence of the changes of their main descriptive parameters values. Indeed, while being operated nonlinear effects observed with loudspeakers are due to changes of such constitutive parameters. Regarding either current or voltage-drive, an original model based on Simulink R is presented, taking account of all the electrical and mechanical properties closely associated with nonlinear behaviours. Moreover, as such a Simulink R model may be combined with the PSpice R advanced software, the behaviour of both loudspeaker and amplifier can be exhaustively investigated and optimized. To this end, the amplifier is simulated thanks to the Orcad-Capture-PSpiceR software prior to match with the loudspeaker model with the so-called SLPS co-simulator. Then, values of the current flowing through the loudspeaker can be determined and plotted considering voltage controlling. Obviously in this case current-drive has not to be assessed. This way to proceed allows us to highlight any critical information especially due to the voice coil displacement, yielded velocity, and acceleration of the diaphragm. Indeed our approach testifies to the imperative necessity of mechanical measurements together with electrical ones. Then, considering a given amplifier-loudspeaker association with specific parameters changes of the latter, the entailed nonlinear distortion allows us to qualify and criticize the whole design. Such an original approach should be most valuable so as to match the best fitted amplifier with a given electrodynamic loudspeaker. Then non linear effects due to voltage and current-drive are compared highlighting the advantages of an apt currentcontroled policy.
The paper presents descriptions of bridge disintegration types and contact mass loss in the bridge stage. There is presented Matlab solvers to solve equation describing dynamic changes of temperature in the bridge region. The final result of program calculations is the mass loss and the volume of the metal of contacts which was lost during the bridge stage.
Simulation software dedicated for design of casting processes is usually tested and calibrated by comparisons of shrinkage defects
distribution predicted by the modelling with that observed in real castings produced in a given foundry. However, a large amount of
expertise obtained from different foundries, including especially made experiments, is available from literature, in the form of
recommendations for design of the rigging systems. This kind of information can be also used for assessment of the simulation predictions.
In the present work two parameters used in the design of feeding systems are considered: feeding ranges in horizontal and vertical plates as
well as efficiency (yield) of feeders of various shapes. The simulation tests were conducted using especially designed steel and aluminium
castings with risers and a commercial FDM based software. It was found that the simulations cannot predict appearance of shrinkage
porosity in horizontal and vertical plates of even cross-sections which would mean, that the feeding ranges are practically unlimited. The
yield of all types of feeders obtained from the simulations appeared to be much higher than that reported in the literature. It can be
concluded that the feeding flow modelling included in the tested software does not reflect phenomena responsible for the feeding processes
in real castings properly. Further tests, with different types of software and more fundamental studies on the feeding process modelling
would be desirable.
The demand for castings of high quality and sound work is nowadays very high. The production of sound castings without foundry errors is the big issue in modern foundries. Foundry simulation software can do a lot to help improve the disposition of castings, gating system and feeder system, and assure good filling and solidification conditions, and also produce sound casting without the need of the old method of "try and error". One can easily change a lot of parameters for filling and solidification, and create the best proposal for production. Connor inlets have two functions. One is that it serves as an ingate, through which molten metal passes and comes into the mould cavity. The second function is that it serves as a feeder and substitutes the metal contracted during solidification and cooling of the castings. It can also save quite a lot of metal in comparison to classic feeders.
A model-based approach, the Model-View-Interactor Paradigm, for automatic generation of user interfaces in software frameworks for measurement systems is proposed. The Model-View-Interactor Paradigm is focused on the "interaction" typical in a software framework for measurement applications: the final user interacts with the automatic measurement system executing a suitable high-level script previously written by a test engineer. According to the main design goal of frameworks, the proposed approach allows the user interfaces to be separated easily from the application logic for enhancing the flexibility and reusability of the software. As a practical case study, this approach has been applied to the flexible software framework for magnetic measurements at the European Organization for Nuclear research (CERN). In particular, experimental results about the scenario of permeability measurements are reported.
The article refers to the idea of using the software defined network (SDN) as an effective hardware and software platform enabling the creation and dynamic management of distributed ICT infrastructure supporting the rapid prototyping process. The authors proposed a new layered reference model remote distributed rapid prototyping that allows the development of heterogeneous, open systems of rapid prototyping in a distributed environment. Next, the implementation of this model was presented in which the functioning of the bottom layers of the model is based on the SDN architecture. Laboratory tests were carried out for this implementation which allowed to verify the proposed model in the real environment, as well as determine its potential and possibilities for further development. Thus, the approach described in the paper may contribute to the development and improvement of the efficiency of rapid prototyping processes which individual components are located in remote industrial, research and development units. Thanks to this, it will be possible to better integrate production processes as well as optimize the costs associated with prototyping. The proposed solution is also a response in this regard to the needs of industry 4.0 in the area of creating scalable, controllable and reliable platforms.
The article presents the issue related with a proper preparation of a data sheet for the
analysis, the way of verifying the correctness and reliability of input information, and proper
data encoding. Improper input or coding of data can significantly influence the correctness
of performed analyses or extend their time. This stage of an analysis is presented by an
authorship questionnaire for the study on occupational safety culture in a manufacturing
plant, using the Statistica software for analyses. There were used real data, obtained during
the research on the issue of occupational safety and factors having the greatest influence on
the state of occupational safety.
In recent years, power systems have been pushed to operate above their limits due to the increase in the demand for energy supply and its usage. This increase is accompanied by various kinds of obstructions in power transmission systems. A power system is said to be secured when it is free from danger or risk. Power systems security deals with the ability of the system to withstand any contingencies without any consequences. Contingencies are potentially harmful disturbances which occur during the steady state operation of a power system. Load flow constitutes the most important study in a power system for planning, operation, and expansion. Contingency selection is performed by calculating two kinds of performance indices; an active performance index (PIP) and reactive power performance index (PIV) for a single transmission line outage. In this paper, with the help of the Newton Raphson method, the PIP and PIV were calculated with DIgSILENT Power Factory simulation software and contingency ranking was performed. Based on the load flow results and performance indexes, the Ethiopian Electric Power (EEP) North-West region network is recommended for an upgrade or the reactive power or series compensators should be constructed on the riskiest lines and substations.
A new ultrasound digital transcranial Doppler system (digiTDS) is introduced. The digiTDS enables diagnosis of intracranial vessels which are rather difficult to penetrate for standard systems. The device can display a color map of flow velocities (in time-depth domain) and a spectrogram of a Doppler signal obtained at particular depth. The system offers a multigate processing which allows to display a number of spectrograms simultaneously and to reconstruct a flow velocity profile.
The digital signal processing in digiTDS is partitioned between hardware and software parts. The hardware part (based on FPGA) executes a signal demodulation and reduces data stream. The software part (PC) performs the Doppler processing and display tasks. The hardware-software partitioning allowed to build a flexible Doppler platform at a relatively low cost.
The digiTDS design fulfills all necessary medical standards being a new useful tool in the transcranial field as well as in heart velocimetry research.
In recent years, the increasing threat to ground water quality due to human activities has become a matter of great con-cern. The ground water quality problems present today are caused by contamination and by over exploitation or by combination of both. Reverse osmosis (RO) desalination is one of the main technologies for producing fresh water from sea water and brackish ground water.
Algeria is one of the countries which suffer from the water shortage since many years, so desalination technology becomes inevitable solution to this matter.
In this study, a comparison is provided of results of reverse osmosis desalination for three different qualities of brack-ish water from the central-east region of Algeria (Bouira and Setif Prefectures), wherein they cannot use it as human drink-ing or in irrigation systems. The main objective of our study is to establish a comparison of the reverse osmosis membrane TW30-2540 performances in the term of (permeate flow, recovery rate, permeate total dissolved solids – TDS and salts re-jection) under different operation pressures (each one takes a time of 720 second for pilot scaling). In order to make an overview comparison between the experimental and the simulated results we used ROSA (Reverse Osmosis System Analy-sis) software.
At the end of this study we noted that, the simulated results are lower than the pilot scaling values and the most re-moved salts are the sodium chlorides with 99.05% of rejection rate.
In the age of Information and Communication Technology (ICT), Web and the Internet have changed significantly the way applications are developed, deployed and used. One of recent trends is modern design of web-applications based on SOA. This process is based on the composition of existing web services into a single scenario from the point of view of a particular user or client. This allows IT companies to shorten the product-time to market process. On the other hand, it raises questions about the quality of the application, trade-offs between quality factors and attributes and measurements of these. Services are usually hosted and executed in an environment managed by its provider that assures the quality attributes such as availability or throughput. Therefore, in this paper an attempt has been made to perform quality measurements towards the creation of efficient, dependable and user-oriented Web applications. First, the process of designing service-based applications is described. Next, metrics for subsequent measurements of efficiency, dependability and usability of distributed applications are presented. These metrics will assess the efforts and trade-offs in a Web-based application development. As examples, we describe a pair of multimedia applications which we have developed in our department and executed in a cluster-based environment. One of them runs in the BeesyCluster middleware and the second one in the Kaskada platform. For these applications we present results of measurements and conclude about relations between quality attributes in the presented application development model. This knowledge can be used to reason about such relations for new similar applications and be used in rapid and quality development of the latter.
In the existent world of continuous production systems, strong attention has been waged
to anonymous risk that probably generates significant apprehension. The forecast for net
present value is extremely important for any production plant. The objective of this paper
is to implement Monte Carlo simulation technique for perceiving the impact of risk and uncertainty
in prediction and forecasting company’s profitability. The production unit under
study is interested to make the initial investment by installing an additional spray dryer
plant. The expressive values acquied from the Monte Carlo technique established a range of
certain results. The expected net present value of the cash flow is $14,605, hence the frequency
chart outcomes confirmed that there is the highest level of certainty that the company
will achieve its target. To forecast the net present value for the next period, the results
confirmed that there are 50.73% chances of achieving the outcomes. Considering the minimum
and maximum values at 80% certainty level, it was observed that 80% chances exist
that expected outcomes will be between $5,830 and $22,587. The model’s sensitivity results
validated that cash inflows had a greater sensitivity level of 21.1% and the cash inflows for
the next year as 19.7%. Cumulative frequency distribution confirmed that the probability
to achieve a maximum value of $23,520 is 90 % and for the value of $6,244 it is about 10 %.
These validations suggested that controlling the expenditures, the company’s outflows can
also be controlled definitely.
We demonstrate a modularity bug in the interface system of Java 8 on the practical example of a textbook design of a modular interface for vector spaces. Our example originates in our teaching of modular object-oriented design in Java 8 to undergraduate students, simply following standard programming practices and mathematical denitions. The bug shows up as a compilation error and should be xed with a language extension due to the importance of best practices (design delity).
The chapter deals with the issue of the risk and security management process in public administration, according to the internal audit standards and their requirements. Main legal acts and standards were specified and shortly described. Specially the risk analysis process and security measures selection were emphasized. The possibility to use the software tools for the risk analysis and security measures selection support in public administration was presented. The experiment of OSCAD usage in public administration was shortly described and its results were presented. This experiment shows that the software primarily intended for IT Security Management can be used for risk management in different area as well, for example – in public administration. Some possibilities of further development of risk management supporting tools were proposed.