Constant factor delta modulation - a new instantaneously adaptive delta modulation system

A new model of an instantaneously adaptive delta modulator called hero a "CONSTANT FACTOR DELTA MODULATOR", (abbreviated C.F.D.M.) has been developed and the selection of suitable constant factors (adaptation constants) with its adaptation logic has been described. The basic delta modulator has been adapted to give an improved performance by introducing a small memory and prediction method in the feedback loop thereby enabling the coder to adapt to the instantaneous variations in the analogue input signal. This C.F.D.M. model of adaptive system adapts its step size, at every sampling instant r, as a result of the detection of the four possible binary groups formed from the last three binary values transmitted. The adaptation constant which is the ratio of-the present step size mr, to the previous step size mr-l, can have, at any sampling instant, one of four values with a magnitude of Ai; A2, A3 and A4, corresponding to the four different possible groups formed. The polarity of the present step size is the same as the present binary value Lr. The effect of this C.F.D.M. system is that for a given decoded signal to noise ratio, the necessary bandwidth of the transmission channel is reduced. The C.F.D.M. described here gives an improved overall coding characteristic and removes an objectionable hunting characteristic compared to the one-bit memory adaptive DM by JAYANT(13). It offers wider dynamic range for the bandlimited Gaussian Input. The results are compared with other similar schemes on adaptive delta modulators and computer plotted graphs are presented whenever necessary. From these results and responses, the C.F.D.M. seems to be promising for encoding video-signals. Several computer simulations have been made for the design of the Constant Factor delta modulator, JAYANT's CODER, WINKLER's H.I.D.M. coder and linear delta modulator. The performances of these coders have been compared. A considerable number of computer simulation results are presented which relate to digital low-pass filter and the estimation of power spectra

Development of an Instrumentation System for a Laboratory Model Food Product Dryer

To achieve optimal dryer performance, the process parameters required for both the optimization and control of the drying process must be made available via the instrumentation system. A few works have been reported on the development of instrumentation systems for handling drying system parameters. Out of which, some are deficient in the number of drying process parameters that can be handled, while others are unreliable and inaccurate. Therefore, there is the need to develop a microcontroller-based instrumentation system that can monitor, measure, control, display and store the main drying process parameters and sample weight with a high degree of reliability and accuracy. In this study, the sensors were selected based on system specifications and interfaced with the microcontroller. The codes for controlling, logging and displaying of drying parameters were developed and installed on the microcontroller. When tested at steady-state conditions, the system yielded satisfactory results with maximum control and detection errors being 2.0% and 1.8% for the temperature and sample weight, respectively. The developed system can be used for efficient computation of both the dry and wet basis sample moisture content values and also detect the set sample weight. Keywords— Dryer, Drying parameters, Instrumentation system, Moisture content, Sensor

An Alternative Electrode System for Monitoring Belousov-Zhabotinsky Chemical Oscillations

The capability of copper-platinum (Cu/Pt) electrode system as a BelousovZhabotinsky (BZ) chemical oscillation monitor was compared with that of the normally used SCE/Pt electrode system, by testing it on three BZ systems, which were obtained by varying the oscillator in the combination bromate, oscillator and malonic acid. The oscillators, used separately, were cerium(IV), manganese(II) and ferroin [iron (II)-1,10- phenanthroline complex].Cu/Pt electrode gave essentially identical values of oscillation characteristics (oscillation period, peak potential, induction period, peak width) except peak potentials. This indicated that the Cu/Pt electrode system would be more useful than the SCE/Pt electrode system (which had chloride leakage problem), in electrical applications of chemical oscillations, such as electrical switches, which would depend only on the on/off frequency

A Potential Model for Chemical Oscillations

Oscillation characteristics: induction period, oscillation period, peak potential, and total oscillation time of Belousov-Zhabotinsky systems, which consisted of bromate - oscillator [Ce4+ or Mn2+ or ferroin] - malonic acid were deter- mined using SCE/Pt and Cu/Pt electrodes. The solution potential requirements for appearance of chemical oscillations were determined by finding the concentra- tion limits of the reactants, bromate and malonic acid, and measuring the corres-ponding solution reduction potentials. A chemical oscillation model was proposed

Innovative prefabricated modular structures – an Overview and life cycle energy analysis

Speed of construction and improved environmental performance are two critical concerns which modern construction industry pays a significant amount of attention on. Employing innovative prefabricated modular structures is one key strategy used to achieve these goals. However, there is an absence of detailed scientific research or case studies dealing with the potential environmental benefits of prefabrication, particularly in the areas of embodied energy savings resulting from waste reduction and improved efficiency of material usage. This paper gives a brief overview of prefabricated modular structures and aims to quantify the embodied energy of modular prefabricated steel and timber multi-residential buildings in order to determine whether this form of construction provides improved environmental performance over conventional concrete construction methods. A case study was carried out on an eight-storey, 3943 m2 multi-residential building. It was found that a steel-structured prefabricated system resulted in a significantly reduced material consumption of up to 78% by mass compared to conventional concrete construction. However, the prefabricated steel building resulted in an increase (~50%) in embodied energy compared to the concrete building. This form of construction has the potential to contribute significantly towards improved environmental sustainability in the construction industry

Ground-coupled cooling in Hanoi

The energy required for space cooling could be reduced by using ground as a heat sink depending on the weather conditions and the ground characteristics. In this paper the theoretical performance of a closed loop ground coupled cooling system for a commercial building in Hanoi has been investigated as an alternative to the conventional air-to-air cooling system. A theoretical computational model for the prediction of the cooling system performance has been developed. It was found that the ground-coupled cooling system performs better (approximately 30% energy saving) than a conventional air-to-air cooling system

Entrepreneurial Success through Microfinance Services among Women Entrepreneurs in Sri Lanka: A Pilot Study and Overview of the Findings

Determining microfinance services which facilitate entrepreneurial success among women entrepreneurs who use such services remains a major issue in the microfinance sector. To address this gap, this study was designed to tap into microfinance services constructs as well as entrepreneurial success of women entrepreneurs within the conceptual model. The relevant questionnaire was piloted among 40 women through microfinance services in Sri Lanka. Based on theories, the measures which comprise microcredit, micro-saving, micro-insurance, business-support, skills development and dependent variable of the entrepreneurial success among women through micro finance were derived from the literature and expert opinion. These constructs were subject to reliability and validity tests to decide on the measures and items to be retained to represent microfinance services and entrepreneurial success in microfinance sector in Sri Lanka. The findings of the study will provide a good starting point to identify the suitable measurements. Further the study will pave way for a comprehensive study which can develop a diamond specification model for the financial sector in Sri Lanka. Keywords: Entrepreneurial success, Microfinance Services, Women in Sri Lanka. JEL Classifications: G21, L2

Development of Electromagnet for Laboratory Water Treatment Experiments

Water is said to be magnetized when it flows across the magnetic field and magnetized water finds its application in many areas of life. Despite the numerous benefits of magnetized water, very little works have been reported on the development of magnet for water magnetizer application. In most of the reported works, the detailed theoretical analysis and design procedure required for the development of the magnet was not accounted for; hence the need for the present study. Electromagnetic means of producing flux density is considered in this study due to its advantage of flux density variation, which is not achievable with the use of its permanent magnet counterparts. The design equation of short electromagnet was derived from the existing equations of coil magnetic flux density and then used for the air core electromagnet design. The variation of the magnetic flux density with the distance between two electromagnets was empirically investigated. The performance of the developed electromagnet is satisfactory, as the flux density varies between 814.6 and 510G corresponding to the gap (0 - 4cm) between the coils (i.e., water pipe diameter). Keywords— Air core, Coils, Iron core, Magnetic flux density, Magnetized wate

Efficacy and effectiveness of dihydroartemisinin-piperaquine versus artesunate-mefloquine in falciparum malaria: an open-label randomised comparison.

BACKGROUND: Artemisinin-based combinations are judged the best treatments for multidrug-resistant Plasmodium falciparum malaria. Artesunate-mefloquine is widely recommended in southeast Asia, but its high cost and tolerability profile remain obstacles to widespread deployment. To assess whether dihydroartemisinin-piperaquine is a suitable alternative to artesunate-mefloquine, we compared the safety, tolerability, efficacy, and effectiveness of the two regimens for the treatment of uncomplicated falciparum in western Myanmar (Burma). METHODS: We did an open randomised comparison of 3-day regimens of artesunate-mefloquine (12/25 mg/kg) versus dihydroartemisinin-piperaquine (6.3/50 mg/kg) for the treatment of children aged 1 year or older and in adults with uncomplicated falciparum malaria in Rakhine State, western Myanmar. Within each group, patients were randomly assigned supervised or non-supervised treatment. The primary endpoint was the PCR-confirmed parasitological failure rate by day 42. Failure rates at day 42 were estimated by Kaplan-Meier survival analysis. This study is registered as an International Standard Randomised Controlled Trial, number ISRCTN27914471. FINDINGS: Of 652 patients enrolled, 327 were assigned dihydroartemisinin-piperaquine (156 supervised and 171 not supervised), and 325 artesunate-mefloquine (162 and 163, respectively). 16 patients were lost to follow-up, and one patient died 22 days after receiving dihydroartemisinin-piperaquine. Recrudescent parasitaemias were confirmed in only two patients; the day 42 failure rate was 0.6% (95% CI 0.2-2.5) for dihydroartemisinin-piperaquine and 0 (0-1.2) for artesunate-mefloquine. Whole-blood piperaquine concentrations at day 7 were similar for patients with observed and non-observed dihydroartemisinin-piperaquine treatment. Gametocytaemia developed more frequently in patients who had received dihydroartemisinin-piperaquine than in those on artesunate-mefloquine: day 7, 18 (10%) of 188 versus five (2%) of 218; relative risk 4.2 (1.6-11.0) p=0.011. INTERPRETATION: Dihydroartemisinin-piperaquine is a highly efficacious and inexpensive treatment of multidrug-resistant falciparum malaria and is well tolerated by all age groups. The effectiveness of the unsupervised treatment, as in the usual context of use, equalled its supervised efficacy, indicating good adherence without supervision. Dihydroartemisinin-piperaquine is a good alternative to artesunate-mefloquine