BER Performance of IM/DD FSO System with OOK using APD Receiver

In this paper, the performance of intensity-modulated with direct detection (IM/DD) free space optical (FSO) system using the on-off keying (OOK) and avalanche photodiode (APD) receiver is observed. The gamma-gamma model is used to describe the effect of atmospheric turbulence since it provides good agreement in the wide range of atmospheric conditions. In addition, the same FSO system with equal gain combining applied at the reception is analyzed. After theoretical derivation of the expression for the bit error rate (BER), the numerical integration with previously specified relative calculation error is performed. Numerical results are presented and confirmed by Monte Carlo simulations. The effects of the FSO link and receiver parameters on the BER performance are discussed. The results illustrate that the optimal APD gain in the minimum BER sense depends considerably on the link distance, atmospheric turbulence strength and receiver temperature. In addition, the value of this optimal gain is slightly different in the case of spatial diversity application compared with single channel reception

Drying processes of lignites with high moisture content in packed and fluidized bed

Уклањање влаге из нискоквалитетних угљева се сматра важним поступком побољшања квалитета угља. У раду је приказан преглед тренутног стања технологија оплемењивања нискоквалитетних угљева, са посебним нагласком на процесе сушења као и одстрањивања влаге (у течном стању). Да би се израчунали значајни параметри процеса уклањања влаге развијен је и представљен модел конвективног сушења угља у флуидизованом слоју, заснован на двофазном моделу мехурастог флуидизованог слоја са гасом и честицама у суспензионој фази и гасом у мехурастој фази. Основна концепција развијеног модела је да се процес сушења у суспензионој фази разматра као за непокретни слој честица, коришћењем концепта "коефицијент сушења", при чему се врши прорачун за елементарне слојеве (запремине) и уопштава за цео слој честица. Мешање честица које се јавља у флуидизованом слоју урачунава се преко дифузионог члана у диференцијалним једначинама. Топлотна проводљивост непокретног слоја коју су дефинисали Zehner, Bauer и Schlünder је коришћена за дефинисање механизама преноса топлоте који се јављају у суспензионој фази флуидизованог слоја. Дискретизација система диференцијалних једначина извршена је нумеричком методом контролних запремина. Добијени систем линеаризованих алгебарских једначина је решаван помоћу ТДМА алгоритма (Три- Дијагонални Матрични Алгоритам). Релације зависне од материјала (пренос супстанције унутар чврсте фазе, равнотежно стање влаге између гасне и чврсте фазе), које се односе на одговарајућу врсту угља (лигнит Колубара), добијене су претходним истраживањима...Removal of moisture from low-rank coals is deemed an important quality upgrading method. An overview of the current status of low-rank coal upgrading technologies is presented in the paper, particularly with respect to drying and dewatering procedures. In order to calculate the significant parameters of the moisture removal process, a model of convective coal drying in a fluid bed, based on the two-phase bubbling fluidization model with gas and particles in suspension phase and gas in bubbling phase, is developed and presented. Basic assumption of the model is that the drying process in suspension phase is considered as for packed bed of particles by applying concept "drying coefficient", where the calculation is performed for elementary layers (volumes) and generalized for the entire bed of particles. The mixing of particles is calculated by means of diffusion term in the differntial equations. Effective thermal conductivity of the packed bed as defined by Zehner/Bauer/Schlünder is used to define heat transfer mechanisms occurring in the suspension phase of the fluid bed. A control volume numerical method is used for discretization of the differntial equations. Discretization equations have been solved by means of TriDiagonal-Matrix Algorithm. Product-specific data (intraparticle substance transfer, gas-solid moisture equilibrium) related to the particular coal variety addressed here (Kolubara lignite) are obtained through preliminary investigations. Тwo series of experimens in fluidized bed and one series in packed bed were performed. A completely new set of experimental results obtained has been successfully used to validate the model additionally. Comparison of obtained numerical simulation results and experimental results and results of other authors from available literature have shown a good agreement..

Influence of dietary mannanoligosaccharides on histological parameters of the jejunal mucosa and growth performance of broiler chickens

The trial involved 480 Hubbard Classic broiler chicks which were from either mannanoligosaccharide (MOS) fed breeder flock (Bio-Mos, Alltech Inc. USA at level of 1 kg/t) or control fed breeder flock (without MOS). Three groups with four replicates per treatment were formed: control fed breeders/control fed broilers (C/C); MOS fed breeders/control fed broilers (BM/C) and MOS fed breeders/MOS fed broilers (BM/BM). All chicks were fed the same basal diet, except for the inclusion of Bio-Mos (1, 0.75 and 0.5 kg/t in the starter, grower and finisher diet, respectively). The results showed a significant improvement (p<0.05) in the body weight gain with the addition of Bio-Mos in broiler feed. Feed conversion ratio was improved by 0.03 points, but the difference was not significant (P>0.05). The gut morphology examination showed that chick origin (chicks that originated from Bio-Mos fed breeders or control fed breeders) did not influence the morphological parameters of the jejunum in the broiler chickens, but addition of Bio-Mos directly to the broiler feed had a significant influence on the gut morphology and played an important role in processes of digestion and absorption, leading to improved performance.Key words: Broiler, mannanoligosaccharides, growth, jejunum, histology

Prediction of metabolisable energy of poultry feeds by estimating in vitro organic matter digestibility

The aim of this study was to develop equations to predict the in vivo apparent metabolisable energy (AME) of poultry feeds using an in vitro method for estimation of organic matter digestibility. In this study, a total of 57 samples of feedstuffs and 23 samples complete diets for poultry were used. Dry matter (DM), crude protein (CP), crude fibre (CF), crude fat (CFat) and crude ash (CA) of the diets were determined. A modified method for estimating the enzymatic digestibility of organic matter (EDOM) was used. For the determination of in vivo ME, the rooster digestibility assay was followed. Obtained laboratory results, that is in vitro and proximate analysis values were regressed against the in vivo ME values and equations for predicting the in vivo ME of feeds for poultry have been derived. Using CA, CF, CFat and in vitro EDOM as predictors, the following equation for predicting the in vivo ME in poultry feeds was derived: ME (MJ/kg DM) = 5.46 – 0.2166 x CA – 0.0946 x CF + 0.2219 x CFat + 0.1054 x EDOM (R2 = 0.844, RSD = 1.10). Using only EDOM as predictor generated the equation: ME (MJ/kg DM) = -0.41 + 0.1769 x EDOM (R2 = 0.689; RSD = 1.63). Results show that using only EDOM as a predictor was not as accurate as when the other variables were included.Key words: Metabolisable energy, prediction, poultry, feeds, organic matter digestibilit

Changes in Crude Protein Content with Advancing Maturity in Lucerne

The main determinants of the quality of lucerne forage are digestibility and protein content (Julier et al., 2001) as well as crude fibre content. In the early vegetative phases, the crude protein content of the leaves and stems is the highest and crude fibre content the lowest (Katic et al., 2003). The aim of this study was to determine the rate of change in crude protein levels at different stages of growth and development

Agronomic Characteristics of Novi Sad Winter Vetch Cultivars

Genus Vicia. contains important annual food and forage species such as field bean, V. faba., narbon vetch, V. narbonensis, and common vetch, V. sativa (Maxted, 1995), while Hungarian V. pannonica Crantz and hairy vetch V. villosa also play an important role in the Balkans. Winter vetches are excellent forage catch crops useful for sustainable agriculture and organic farming (Ċupina et al., 2004). Our study was aimed at determining the agronomic characteristics of the winter vetch cultivars developed in Novi Sad, assessing thus their ability for successful growing in the prevailing conditions of Serbia and Montenegro

Interfacial Polarization and Dielectric Properties of Epoxy/Graphite Flakes Composites

Dielectric properties of composites based on bisphenol-A-epoxy resin loaded with various content of graphite flakes (GF) have been studied. The dielectric permeability, tangent loss and ac conductivity have been examined in wide temperature (170 – 370 K) and frequency (20 Hz – 200 kHz) range. In composites loaded with GF flakes up to 10 wt.%, the dominant conduction mechanism is tunneling of electrons, while loading of 15 wt.% gives rise to electron conduction through direct contacts between fillers. Dielectric properties of composites are largely determined by the nature of the filler/matrix interface, the filler surface area and the inherent conductivity of the fillers. At low electric field frequencies, dominates socalled interfacial (or space charge) polarization due to accumulation of free charges at the interfaces between two phases (filler and matrix), which differ in electrical conductivity.Influence of the filler surface chemistry have been studied for composites loaded with 5 wt.% graphite flakes obtained: (i) under wet milling, without (GF) or with (GF-Tr100x) adding Triton-100x as a surfactant, or (ii) under dry milling in the presence of KOH (GF-KOH). The surface treatment with KOH notable increased dielectric constant of the epoxy/GF-KOH5 composite, keeping low tangent loss, comparable to the counterpart, the epoxy/GF5 composite

Effect of water stress on yield and evapotranspiration of sunflower

An experiment was conducted at Rimski Šančevi Experiment Field of Institute of Field and Vegetable Crops in Novi Sad during 2000 - 2005. The soil in the experimental plot was calcareous chernozem on loess terrace. Using the yield response factor (ky), the study investigated how sunflower yield and evapotranspiration were affected by deficit of available soil water during the growing season. The experiment consisted of an irrigated treatment (T1), in which irrigation was used when soil moisture levels dropped to 60-65% of FC (field capacity), and a nonirrigated control treatment (T0). The sunflower hybrid used in the study was NS-H-111. On average, no significant differences in yield level were observed between T1 (3.79 t ha-1) and T0 (3.75 t ha-1) treatments. Seasonal evapotranspiration (ETm) obtained in T1 treatment was in the 402-479 mm range. The yield response factor (ky) was obtained as 0.20 for total growing season and 0.27, 0.31 and 0.48 for vegetative, flowering and yield formation period, respectively. Period from flowering to maturity was the most sensitive towards water deficiency

Data-driven vs knowledge-driven inference of health outcomes in the ageing population: A case study

Preventive, Predictive, Personalised and Participative (P4) medicine has the potential to not only vastly improve people's quality of life, but also to significantly reduce healthcare costs and improve its efficiency. Our research focuses on age-related diseases and explores the opportunities offered by a data-driven approach to predict wellness states of ageing individuals, in contrast to the commonly adopted knowledge-driven approach that relies on easy-to-interpret metrics manually introduced by clinical experts. This is done by means of machine learning models applied on the My Smart Age with HIV (MySAwH) dataset, which is collected through a relatively new approach especially for older HIV patient cohorts. This includes Patient Related Outcomes values from mobile smartphone apps and activity traces from commercial-grade activity loggers. Our results show better predictive performance for the data-driven approach. We also show that a post hoc interpretation method applied to the predictive models can provide intelligible explanations that enable new forms of personalised and preventive medicine

Effect of phytase supplementation on growing pigs performance

Dietary concentrations of phytate are crucial for its anti-nutritive properties and its negative impact on P availability. The increase of dietary phytate level is shown to increase endogenous losses of amino acids and minerals in pigs. The partial availability of the P component of phytate to simple-stomached species attains importance as the world's rock phosphate reserves are not renewable, which could lead to a P supply crisis in the future. Supplementing phytase is becoming increasingly common as a method to improve the availability of P in plant ingredients containing high levels of phytate P. Fourty-eight pigs (Swedish Landrace boars × Dutch landrace sows) weaned at day 35 with an initial BW of 8.72±0.28 kg were used for a 40-day weaner performance study. The study was structured as a complete randomized design to evaluate the response of weaner pigs to four concentrations of microbial phytase produced by Aspergillus niger: (T1) basal diet; (T2) basal diet + 1000 FTU/kg; (T3) diet with decreased dicalcium phosphate + 1000 FTU/kg; and (T4) diet with no dicalcium phosphate + 1000 FTU/kg. Control group of piglets (T1) has achieved standard body mass while addition of phytase in meal increased body mass by 6.59% in T2 and 7.52% in T3. Phytase supplementation prevented decreased body weight gain diets where available phosphorous level was reduced by 50. The amount of consumed feed per day was not significantly different. Feed efficiency of T2 and T3 groups was by 3.23% better and of T4 for 11.29% lower compared to the control group of piglets (T1). Lower production results achieved by the use of low phosphorous diets can be avoided to a certain level by the use of microbial phytase. The use of phytase in pig diet significantly improved phosphorous availability, as well as of other mineral substances from the phytate complex. [Projekat Ministarstva nauke Republike Srbije, br. III46002