Traditional Passive Methods Research Articles

Hybrid manipulation of inkjet-printing deposition pattern of high particle concentration droplet by means of thermal and binary solvent effects

Inkjet-printing of functional material is a well-known drop-on-demand technology used in a wide range of modern applications, such as flexible electronics, biomedical testing, etc. It enables to deliver small amount of materials as ink to the specific location on target substrates. However, it is challenging to precisely manipulate the particle deposition characteristics which is crucial to the quality of the fabricated device. Unlike the traditional passive methods by manipulating the nanoparticle, solvent or substrate surface condition, we propose a passive-active hybrid manipulation method by employing a binary mixture solvent and heating substrate. In this paper, the effects of the solvent mixing ratio, the substrate temperature, the substrate thermal properties on the deposition characteristics of high concentration ITO nano-ink were investigated. Interestingly, we have observed a transition of the classic slim coffee-ring to a fat coffee-ring with a large ring width. A dimensionless number was developed to predict the transition boundary from fat-ring pattern to slim-ring pattern. Finally, the phase diagrams of deposition patterns on three substrates were developed, which were convenient for deposition pattern manipulation in real applications.

Game theme based instructional module to teach loops and choice statements in computer science courses

With the fast development of computer science and technology, computer games have become one of the integral parts of modern way of living. Research studies have conveyed that educational games are motivating, engaging and provide a reliable learning context. Due to the expansion of the educational transform, game theme-based learning methodology has become one of the current research focuses. There is a need to change the traditional passive method of teaching to an active method of teaching such as game and simulation-based learning. So, we need to provide a better learning environment by increasing the student's motivation towards learning. The game theme-based instructional (GTI) modules prepare the learners to think critically, and the students can adopt new challenges of the relevant knowledge. This paper presents a novel and exciting methodology of teaching algorithms by motivating the students towards learning. We designed and developed The Ball Targeting Game consisting of two GTI modules to teach loops and choice statements. The gaming modules demonstrated in this paper were developed using Vizard, which is a virtual reality toolkit used for developing virtual worlds and immersive applications for visualization and simulation using Python as its scripting language.

A Model Coupling CFD and DRL: Investigation on Wave Dissipation by Actively Controlled Flat Plate

In order to protect structures along the offshore and off the coast, breakwaters are commonly applied to reduce the influence of waves. Flat plate breakwater is studied frequently due to its great performance near the water surface, however, traditional passive methods such as fixed and floating flat plate breakwaters usually fail to give full play of effective wave dissipation when encountering variable unknown incoming waves. Therefore, this paper develops an interdisciplinary model coupling computational fluid dynamics (CFD) and deep reinforcement learning (DRL) to study the wave dissipation of a submerged movable flat plate breakwater against regular waves. An in-house numerical wave tank (NWT) is built to simulate the fluid-structure interaction between the plate and regular waves. The fluid domain in NWT is regarded as environment while the flat plate breakwater is agent. In addition, the wave dissipation strategy is learned by the artificial neural network (ANN) through the continuous wave-plate interaction. It is excited to find that the coupling model is able to learn the control strategies automatically and exhibits good adaptability to the changes of environment.

Performance improvement of a pulse tube cryocooler with a single compressor through cascade utilization of cold energy

The high-frequency pulse tube cryocooler (HPTC) has been attracting increasing and widespread attention in the field of cryogenic technology because of its compact structure, low vibration, and reliable operation. The gas-coupled HPTC, driven by a single compressor, is currently the simplest and most compact structure. For HPTCs operating below 20 K, in order to obtain the mW cooling capacity, hundreds or even thousands of watts of electrical power are consumed, where radiation heat leakage accounts for a large proportion of their cooling capacity. In this paper, based on SAGE10, a HPTC heat radiation calculation model was first established to study the effects of radiation heat leakage on apparent performance parameters (such as temperature and cooling capacity), and internal parameters (such as enthalpy flow and gas distribution) of the gas-coupled HPTC. An active thermal insulation method of cascade utilization of the cold energy of the system was proposed for the gas-coupled HPTC. Numerical simulations indicate that the reduction of external radiation heat leakage cannot only directly increase the net cooling power, but also decrease the internal gross losses and increase the mass and acoustic power in the lower-temperature section, which further enhances the refrigeration performance. The numerical calculation results were verified by experiments, and the test results showed that the no-load temperature of the developed cryocooler prototype decreased from 15.1 K to 6.4 K, and the relative Carnot efficiency at 15.5 K increased from 0.029% to 0.996% when substituting the proposed active method for the traditional passive method with multi-layer thermal insulation materials.

Generating Bessel beams with broad depth-of-field by using phase-only acoustic holograms

We report zero-th and high-order acoustic Bessel beams with broad depth-of-field generated using acoustic holograms. While the transverse field distribution of Bessel beams generated using traditional passive methods is correctly described by a Bessel function, these methods present a common drawback: the axial distribution of the field is not constant, as required for ideal Bessel beams. In this work, we experimentally, numerically and theoretically report acoustic truncated Bessel beams of flat-intensity along their axis in the ultrasound regime using phase-only holograms. In particular, the beams present a uniform field distribution showing an elongated focal length of about 40 wavelengths, while the transverse width of the beam remains smaller than 0.7 wavelengths. The proposed acoustic holograms were compared with 3D-printed fraxicons, a blazed version of axicons. The performance of both phase-only holograms and fraxicons is studied and we found that both lenses produce Bessel beams in a wide range of frequencies. In addition, high-order Bessel beam were generated. We report first order Bessel beams that show a clear phase dislocation along their axis and a vortex with single topological charge. The proposed method may have potential applications in ultrasonic imaging, biomedical ultrasound and particle manipulation applications using passive lenses.

A narrowband active noise control system with a frequency estimation algorithm based on parallel adaptive notch filter

Abstract Active noise control (ANC) instead of traditional passive method shows good low-frequency performance especially for periodic noise signals. To obtain accurate reference signal and remove the secondary feedback effect, frequency estimation algorithms are often used in narrowband ANC systems. In this work, a parallel adaptive notch filter (parallel ANF, PANF) algorithm is proposed to obtain accurate estimation of frequency which is used for generating reference signal in a sinusoidal form. In the proposed PANF algorithm, multiple tones are separated in the feedback reconstruction process to reduce the frequency-interfering effect. As a result, the estimation of multiple frequencies has high accuracy as well as the triangular cascaded ANF (TCANF) algorithm and the computation burden is greatly reduced to the level of the linear cascaded ANF (LCANF) algorithm. Detailed performance analysis is conducted to acquire the deviation of frequency estimation algorithm and the mean square error (MSE) of the ANC system. Finally, extensive simulations and narrowband ANC experiments are carried out in a pipe system to verify theoretical results.

Replacement models in the analysis of intelligent systems

In recent years, the methods of active vibration damping are often used in the construction of the machines. Most vibrations occurring in technical devices have a negative impact on their technical condition. Many methods of vibration reduction are widely known, generally they can be divided into passive methods and active methods. Traditional passive methods consisting in the modification of parameters and structure of existing systems have a number of limitations, among others they do not change in time and have a low efficiency of vibration reduction in the low frequency range. The active vibration dampers that are properly controlled can supply or absorb energy in a specific way behave in a completely different way. This article describe modelling piezoelectric by replacement models represented by appropriately connected elements, eg in mechanical systems in the form of susceptibility or stiffness, are mainly used to simplify a more complicated system or mapping of its actual parameters. In modeling the piezoelectric phenomenon, substitute models with the same input properties as the original systems are used. This publication presents the layout of a piezoelectric plate in the form of an analogous electric circuit composed of electrical components. These elements have the appropriate impedance values marked Zij. In order to use the known graph method, the analyzed system was reduced to a substitute system by means of an electric triangle star exchange and methods of structural numbers.

Autofocusing imaging system based on laser ranging and a retina-like sample.

A novel autofocusing method combining active and passive techniques is proposed to improve autofocusing performance. The proposed method is divided into coarse and fine autofocusing stages. First, a laser ranging finder viewed as the active technique is used to obtain a reasonable initial position of the compensating lens group during the coarse autofocusing stage. Second, a retina-like sampling method is used to decrease the volume of processing data during the fine autofocusing stage. We developed a prototype and performed comparative experiments using different targets based on the proposed method and the traditional passive method (TPM). Under optical power of 9×, the TPM consumed 2.5s, while the proposed method performed at 1.3s. The comparative experiments also showed that the proposed method exhibited a better anti-interference property than the traditional method.

Examining Methods Implementers Use in Delivering the HIV/AIDS Programmes in Universities

HIV and AIDS programme implementers or facilitators and lecturers are mandated to use a variety of methods as a means of teaching and distributing HIV and AIDS related information or material to students. The study made use of the Post-positivist paradigm. Thirty- nine lecturers, 24 students, 3 senior health workers and 3 NGO officials made up the sample. Data was collected through questionnaires, face to face interviews, focus group discussions, document analysis, and observations. SPSS computer software was used to analyse quantitative data and qualitative data was grouped into themes. This study revealed that time allocated for HIV and AIDS lessons in the curriculum was not adequate. University lecturers used lecture method, group discussion, assessment methods as key methods of implementing the programme. The study revealed that HIV and AIDS programmes were not well managed or coordinated though they were taught throughout the year in all universities. The study concluded that that a university can teach HIV and AIDS content in different semesters of the academic calendar. It was therefore recommended that HIV and AIDS deserve the political will, recognition and support from designers just like any other subject, move beyond the traditional passive methods and try also video-assisted education models that increase subject’s knowledge significantly and that NGOs and HIV and AIDS coordinators, since they offer technical and financial support, should be conversant with the methods used by the lecturers to a lager extent. DOI: 10.5901/mjss.2014.v5n23p1124

New Smart Passive Graphical Islanding Detection Method

As there is still a great argument on islanding detection methods, this paper presents a new smart passive graphical islanding detection method. The new method depends on measuring the instantaneous variation in phase voltage angle (θ) related to the instantaneous variation in phase voltage magnitude (V) and drawing the relationship between them. The traditional passive methods have performance deficiencies. On the other hand, the active methods are more accurate islanding detection methods, but perturb the electrical system. So, the need for a new detection method which can be accurate, doesn't affect the system behavior, and through which both active and passive methods disadvantages can be avoided is an essential requirement. The continuous updates in Wide Area Monitoring, Protection and Control (WAMPC) technology and Phasor measurement units (PMU) facilitate the idea of measuring and tracing the voltage angle variation. The concept of the new proposed smart passive islanding detection method depends on observing the behavior of the variation of voltage magnitude versus the voltage angle variation (V - θ) of the bus which connects the suggested island with the main power grid. During islanding, sometimes the variation of the voltage magnitude is not significant to be detected, especially in case of low power island. The variation of the voltage angle presents an accurate indication with high sensitivity to the different sorts of system transients. The angle variation behavior differs in load changing, islanding, faulted network, and normal operation conditions. The relationship between (V - θ) is confirmed by the graphical relationship between their derivatives (dV/dt - dθ/dt). V versus θ and dV/dt versus dθ/dt are studied and analyzed in this research to verify the concept of the new method. The new proposed smart method is applied to four different power systems having the same main power grid. The wind electrical power generation unit of the studied power systems has different generation and loading capacities in each of the four studied cases. The studied cases are classified into low, high, and medium (with two different loading status) wind electrical power generation capacity. For each studied case, the system normal operation, load disconnection, islanding, and three phase fault conditions are discussed. In the four studied cases, the results verify the completely different graphical behaviors for each transient condition. So, the concept of the new method is verified.

A novel islanding fault detection for distributed generation systems

SUMMARYThis paper proposes a novel islanding fault detection method for distributed generation systems. Islanding fault detection of distributed generation systems in microgrids and smart grids is an essential security technology. The existing methods for islanding fault detection can be classified as passive methods (such as under/over voltage detection, under/over frequency detection, and voltage phase jump detection, based on natural effects of islanding) and active methods (impedance measurement, slip mode frequency shift, Sandia frequency shift and so on). Once the power consumed by a local load matches the power generated by a local inverter, the islanding phenomenon will be not obvious, and traditional passive methods may fail. In contrast, the active methods can overcome this disadvantage. However, active methods create extra disturbances that may degrade the quality of power generated by the inverter. By reducing the harmonics of the inverter output, coupled with the use of a novel filtering method, the proposed approach can be achieved without additional disturbance and does no nondetection zone islanding detection. In this paper, current harmonic compensation is applied to inverter control to minimize the inverter output harmonics, highlighting on the grid harmonics. Set‐membership filter is developed to estimate the voltage harmonics. Islanding condition is detected by the changes of the specific order harmonics. The effectiveness of the proposed method is demonstrated by simulations. A Kalman filter contrast experiment is presented to confirm that the set‐membership filter can more effectively detect islanding. Copyright © 2013 John Wiley & Sons, Ltd.

System of combined active and passive control of fissile materials and their nuclide composition in nuclear wastes

New methods of non-destructive control must be developed and existing ones must be improved in order to solve the problem of control of fissile materials (FMs) in vessels with nuclear wastes, and to provide safe operation of nuclear power plants. This paper considers the application of active methods of control on the basis of DD or DT pulsed neutron generators. These methods are more comprehensive and sensitive than traditional passive methods for detection of neutron and gamma radiation from nuclear materials, such as U-235 and Pu-239. As a particular method for FM control we use a technique of differential die-away of neutrons, detected by He-3 proportional counters. Calculations performed for 60 litres containers showed the high sensitivity of detection of induced fission neutrons (up to 10 mg of U-235) in a graphite matrix and much lower sensitivity of detection for a container with an iron matrix.

Permafrost Characteristics of the Qinghai‐Tibet Plateau and Methods of Roadbed Construction of Railway

AbstractPermafrost along the Qinghai‐Tibet railway is featured by abundant ground ice and high ground temperature. Under the influence of climate warming and engineering activities, the permafrost is under degradation process. The main difficulty in railway roadbed construction is how to prevent thawing settlement caused by degradation of permafrost Therefore the proactively cooling methods based on controlling solar radiation, heat conductivity and heat convection were adopted instead of the traditional passive methods, which is simply increasing thermal resistance. The cooling methods used in the Qinghai‐Tibet railway construction include sunshine‐shielding roadbeds, crushed rock based roadbeds, roadbeds with rock revetments, duct‐ventilated roadbeds, thermosyphon installed roadbeds and land bridges. The field monitored data show that the cooling methods are effective in protecting the underlying permafrost, the permafrost table was uplifted under the embankments and therefore the roadbed stability was guaranteed.

Using electronic technology for Taenia solium education: educating the educators

In Taenia solium endemic areas, intervention programs include a variety of actions aimed to improve sanitary infrastructure and environment, pig husbandry conditions, detection and treatment of tapeworm carries and cysticercosis cases, among others. For a successful long-term effect, these actions must be associated with community participation and health education programs. Prior to designing/conducting health education programs tailored to specific populations, individuals involved in delivering education, as well as other professionals, students, and community leaders, must be well prepared, their knowledge increased, updated or strengthened. Educators must first be well educated to convey clear and accurate messages. Current electronic technology provides invaluable resources for teaching and learning. Learners using electronic materials benefit from a dynamic, non-linear and flexible interaction that can render long lasting effects compared to traditional passive methods. Electronic resources also provide the capability of producing one standardized template, versatile enough to be adapted, translated, modified, and updated. In this presentation, we introduce our preliminary work on the first interactive media presentation on T. solium which will hopefully, soon, become an interactive tutorial that could be utilized in health education in both developing and developed countries.

Biomechanics Web-Course: An Exploratory Study

From ordering books to searching for cheap airline tickets, the Internet is infiltrating our daily lives. One place where its use is definitely exploding is in the classroom. The Internet affords the instructor the opportunity to provide interactive learning situations in place of more traditional passive methods. This paper discusses the development of an interactive web-based biomechanics module for an undergraduate Introduction to Ergonomics course. An exploratory study found that student performance on a test was equal regardless of whether they were self-taught using web-based material or the textbook. These initial results raise questions as to the characteristics of a successful web-based course.