Synchronization of a renewable energy inverter with the grid

The design, mathematical analysis, and testing results of the architecture of a new all-digital phase-locked loop system for synchronizing a voltage source DC-AC single-phase inverter with the low voltage utility grid are presented. The system which is based on the time-delay digital tanlock loop was simulated using MATLAB/ SIMULINK and was tested by subjecting the grid voltage to various perturbations similar to those which can occur in a real power system, such as voltage sags and nonlinear distortion of the grid voltage waveform. Results indicate that even in the presence of such perturbations the system achieved and/or re-gained synchronization within 100 ms. The proposed system is all-digital and can be readily implemented using a field programmable gate array and easily embedded into a power inverter

Multilevel MPSoC Performance Evaluation: New ISSPT Model

To deploy the enormous hardware resources available in Multi Processor Systems-on-Chip (MPSoC) efficiently, rapidly and accurately, methods of Design Space Exploration (DSE) are needed to evaluate the different design alternatives. In this paper, we present a framework that makes fast simulation and performance evaluation of MPSoC possible early in the design flow, thus reducing the time-to-market. In this framework and within the Transaction Level Modeling (TLM) approach, we present a new definition of ISS level by introducing two complementary modeling sublevels ISST and ISSPT. This later, that we illustrate an arbiter modeling approach that allows a high performance MPSoC communication. A round-robin method is chosen because it is simple, minimizes the communication latency and has an accepted speed-up. Two applications are tested and used to validate our platform: Game of life and JPEG Encoder. The performance of the proposed approach has been analyzed in our platform MPSoC based on multi-MicroBlaze. Simulation results show with ISSPT sublevels gives a high simulation speedup factor of up to 32 with a negligible performance estimation error margin

Multilevel MPSoC Performance Evaluation: New ISSPT Model

To deploy the enormous hardware resources available in Multi Processor Systems-on-Chip (MPSoC) efficiently, rapidly and accurately, methods of Design Space Exploration (DSE) are needed to evaluate the different design alternatives. In this paper, we present a framework that makes fast simulation and performance evaluation of MPSoC possible early in the design flow, thus reducing the time-to-market. In this framework and within the Transaction Level Modeling (TLM) approach, we present a new definition of ISS level by introducing two complementary modeling sublevels ISST and ISSPT. This later, that we illustrate an arbiter modeling approach that allows a high performance MPSoC communication. A round-robin method is chosen because it is simple, minimizes the communication latency and has an accepted speed-up. Two applications are tested and used to validate our platform: Game of life and JPEG Encoder. The performance of the proposed approach has been analyzed in our platform MPSoC based on multi-MicroBlaze. Simulation results show with ISSPT sublevels gives a high simulation speedup factor of up to 32 with a negligible performance estimation error margin. DOI:  http://dx.doi.org/10.11591/telkomnika.v15i1.8085

Modèles D’estimation De L’émission Du Méthane Entérique Des Animaux D’élevage Au Maroc

Enteric CH4 emissions have been of great scientific interest as they represent a real energy loss for livestock and are also responsible for global warming. The objective of this study is to measure enteric methane emissions in farm animals, and then develop models for estimating quantities emitted based on the amount of dry matter ingested (MSI). Holstein cows (n = 38) received dietary rations of 50% forage and 50% feed concentrate, and a linear regression model was developed to predict CH4 production per animal (g). CH4 (animal / day) from the amount of dry matter ingested and the equation obtained was as follows: Y = 19.05X. Here, Y is the amount of CH4 (g CH4 / cow / day) and X is the amount of ingested dry matter (kg), with R² = 0.91, r = 0.97, and RMSPE = 5.53%. For small ruminants (n = 22), three dietary levels were used and methane production was measured. In addition, the equation obtained was: Y = 12.21 X with R² = 0.81, r = 0, 91 and RMSPE = 15.80%. In camelins (n = 12) and equines (n = 10), only one food level was used and methane measurements did not develop an estimation model. However, mean values of methane production were determined and they corresponded to 11.41 g CH4 / kg MSI in camels and 2.18 g CH4 / kg MSI in horses

La plaine du Tafilalet (Sud-est, Maroc) face aux problèmes d'environnement

L’écosystème de la plaine du Tafilalet connaît une multitude de problèmes environnementaux qui menacent son équilibre naturel : la surexploitation des eaux souterraines, la salinité des eaux et des sols, une agriculture basée quasi-exclusivement sur l’irrigation, la dégradation du couvert végétal des forêts naturelles à cause de la forte pression anthropique, la sévérité du climat, la situation géographique, l’ensablement, et une faune sauvage qui nécessite la conservation, ainsi que le contexte socio-économique marqué par le besoin

Calculating coherent light-wave propagation in large heterogeneous media

Understanding the interaction of light with a highly scattering material is essential for optical microscopy of optically thick and heterogeneous biological tissues. Ensemble-averaged analytic solutions cannot provide more than general predictions for relatively simple cases. Yet, biological tissues contain chiral organic molecules and many of the cells' structures are birefringent, a property exploited by polarization microscopy for label-free imaging. Solving Maxwell's equations in such materials is a notoriously hard problem. Here we present an efficient method to determine the propagation of electro-magnetic waves in arbitrary anisotropic materials. We demonstrate how the algorithm enables large scale calculations of the scattered light field in complex birefringent materials, chiral media, and even materials with a negative refractive index

The effect of insulin and calcitonin on osteoblast proliferation and biomineralization

OBJECTIVE: Insulin and calcitonin are involved in bone remodeling. Our aim was to determine the effect of insulin and calcitonin when added separately and in combination to mouse calvarial cultures on osteoblast proliferation and osteoblast mediated biomineralization in medium containing ascorbic acid and beta-glycerol phosphate. Our hypothesis is that both hormones in combination will cause a synergistic increase in osteoblast proliferation and biomineralization. METHODS: Osteoblasts were isolated from neonatal mouse calvaria and cultured under conditions that allow quantification of cellular proliferation and biomineralization. In our proliferation model, osteoblasts were grown in medium containing fetal calf serum stimulated by insulin, calcitonin, both, or culture medium alone that served as control. Proliferation was measured using a hemocytometer (Neubauer cell chamber). Osteoblast biomineralization was estimated by assessing cellular calcium uptake and secreted alkaline phosphatase activity. In the biomineralization model, osteoblasts were grown in the presence of ascorbic acid and betaglycerol phosphate and stimulated by factors used in the proliferation study. Calcium uptake was measured by an Arsenazo III microplate calcium assay and alkaline phosphatase activity was measured by enzyme release from the calvarial cellular layer. Histological and quantitative histomorphometric evaluations measured mineral deposition. RESULTS: Osteoblast proliferation was significantly increased by insulin or calcitonin alone but not by both together. All treatments, especially calcitonin, significantly increased calcium uptake. Only the combination of insulin and calcitonin significantly increased alkaline phosphatase activity. Discussion: Our findings suggest that insulin and calcitonin increase proliferation and biomineralization controlled by osteoblasts.

Antimicrobials in animal agriculture: Parables and policy

In addition to the scientific, economic, regulatory and other policy factors that impact on antimicrobial decision-making in different jurisdictions around the world, there exist ethical, social and cultural bases for the contemporary use of these products in animal agriculture. Thus, the use of the word ‘parable’ to describe the contemporary moral stories that help to guide ethical antimicrobial use practices and broader policy decisions in animal agriculture is appropriate. Several of these stories reflect difficult decisions that arise from conflicting moral imperatives (i.e. both towards animal welfare and towards human health). Understanding the factors that combine to define the past and present paradigms of antimicrobial usage is crucial to mapping a path forward. There exist barriers, as well as opportunities, for advancing scenarios for reducing antimicrobial usage under a variety of voluntary, regulatory and legal policy frameworks. Any new approaches will ideally be structured to extend the use of present-day antimicrobials into the future, to provide novel alternatives for regulating any newly introduced antimicrobial products so as to maximize their useful life span and to ensure the optimal use of these products in animal agriculture to protect not only the health of animals and the interests of animal health/agriculture stakeholders, but also the human health and the interests of the public at large. A full range of policy approaches, which span the realm from strictly enforced regulations and laws to voluntary guidelines and compliance, should be explored with respect to their risks and benefits in a variety of worldwide settings and in full consideration of a range of stakeholder values

Experimental Investigation on Flexural Behaviour of Prefabricated Ultra-Shallow Steel Concrete Composite Slabs

This paper presents the experimental results of four static full-size four-point bending tests to investigate the flexural behaviour of a recently developed prefabricated steel-concrete composite ultra-shallow flooring system (PUSS®). The flooring system comprises of T-ribbed concrete floors partially-embedded within and connected to side C-channel beams and horizontally-oriented shear connectors. This study investigates the effects of three parameters on the flexural behaviour of PUSS and the performance of the shear connectors under bending. The parameters under study are the type of concrete, degree of shear connection and depth of the slab. Four 4m span test specimens are constructed using two types of concrete, two with reinforced normal weight concrete (NWC) and the remaining two with reinforced lightweight aggregates concrete (LWC). Three of the test specimens employ the unique shear connection system composed of horizontally-oriented steel dowels with horizontally-oriented web-welded shear studs (dowels with WWSS) while the last one employs horizontal steel dowels only. The contribution of the above parameters on flexural behaviour and failure mechanisms are examined. The study concludes that replacing NWC with LWC of similar strength does not affect the flexural behaviour of PUSS in terms of slab capacity, ductility and failure mechanism. However, LWC demonstrates lower initial stiffness and leads to the development of larger cracks as loads increases. Also, reducing the degree of shear connection lowers the moment capacity of the slabs and results in failure of some shear connectors during testing. PUSS units exhibit ductile behaviour under bending conditions regardless of the degree of shear connection

COVID-19 Guidelines to Protect Healthcare Workers at Hospitals and Dental Professionals at Dental Office

BACKGROUND፡ Coronavirus disease 2019 is an infectious disease caused by severe acute respiratory syndrome coronavirus 2. This study aimed to address the preventive procedures to protect healthcare workers at hospital to avoid COVID-19, and infection control procedures to protect dental professionals in dental office.METHODS: We conducted a search of published articles from PubMed, google scholar databases using key words such as COVID-19, healthcare worker, infection control, and dental practice. Relevant articles were identified and reviewed. Most published papers were clinical reports and case studies. We have selected some of the current published papers written in English in 2020.RESULTS: Infection control procedures to protect health workers at hospitals, and dental professionals at dental office were summurised and presented. Infection control procedures for healthcare workers at hospitals include Personal protective equipment, Korea filter (KF)94 respirator, goggles, face protector,disposable waterproof long-arm gown, and gloves, and others. Extra-protection procedures should be taken with old and vulnerable healthcare workers. Dental professionals should evaluate patients in advance before starting dental treatment. Aerosols generating procedures should be avoided and personal protective equipment should be used. Dental treatment should be restricted to emergency cases only.CONCLUSION: Old medical staff should be in safer distance to avoid infection, but young physicians and nurses should work at frontline as their immunity is better than their colleagues at old age. Screening patients and measurement of the body temperature are essential measures before dental treatment