Comparison of discrete dynamic pipeline models for operational optimization of District Heating Networks

Optimal operation of District Heating Networks (DHNs) is a very challenging task. One of the main challenges for DHNs optimization tool designers is the choice of an adequate dynamic thermal pipeline model which gives a good tradeoff between accurately modeling the physics of the thermodynamic processes and simultaneously yielding a numerically efficient model. To address this, the paper states the main Partial Differential Equation (PDE) which is used to describe the convection of hot water throughout the literature, together with reasonable assumptions that lead to minor deviations from measurements. Then, different approaches are described which can be used to solve the respective PDE. More specifically, the very common Node Method (NM), approximations of the NM, the lagrangian approach and different Finite Difference (FD) approaches are presented. The main aim of this work is to provide a qualitative and quantitative comparison of these modeling approaches in the context of optimal DHN operation. Our quantitative results show, that by comparing the different approaches to measurement data, the NM yields the smallest modeling errors for most of the temporal discretization sizes. The qualitative comparison identifies that the lagrangian method lacks the differentiability necessary for the implementation in optimization tools. The advantages of the FD approaches include guaranteeing a fixed number of variables, a constant information depth of the temperature distribution along the pipeline and the simplicity of implementation into optimization tools. The approximations of the NM bring benefits when varying mass flow directions need to be considered, which is a crucial aspect in 4t h generation DHNs

Safety and immunogenicity of TetractHib (a vaccine combining DTP vaccine and Haemophilus influenza type b conjugate vaccine) administered to infants at 6, 10 and 14 weeks of age

The safety and immunogenicity of TETRActHIB (a vaccine combining diphtheria and tetanus toxoids-pertussis vaccine (DTP) with Haemophilus influenzae type b (Hib) conjugate vaccine (polyribosyl ribitol phosphate conjugated to tetanus protein) (PRP-T)) was assessed in 131 Cape Town infants immunised at 6, 10 and 14 weeks of age. Serological responses to all component antigens were measured before the first dose and at 18 weeks of age. In addition, anti-PRP antibodies were measured at 9 and 18 months of age to determine long-term immunogenicity. The vaccine was well tolerated by infants and no significant side-effects were reported. Responses to Hib at 18 weeks of age were good in that most infants achieved a level of anti-PRP antibodies <". 0.15 μg/ml, indicative of short-term protection, and 70% achieved a level<". 1 μg/ml, indicative of long-term protection. The proportions of children with protective levels<". 0.15 μg/ml and<". 1 μg/ml were similar at 9 and 18 months of age, i.e. approximately 75% and 45%, respectively. Responses to tetanus and diphtheria toxoids were excellent and all infants achieved protective serological levels. Responses to pertussis were moderate in that approximately 65% achieved 'protective' serum levels of pertussis agglutinins, i.e. titres <". 320. In conclusion, this study has shown that the DTP /PRP-T vaccine is safe, immunogenic and well tolerated in infants immunised at 6, 10 and 14 weeks of age. TETRActHIB is therefore suitable for inclusion in the World Health Organisation Expanded Programme on Immunisation (WHO EPI) schedule

Port-Hamiltonian Modeling of Hydraulics in 4th Generation District Heating Networks

In this paper, we use elements of graph theory and port-Hamiltonian systems to develop a modular dynamic model describing the hydraulic behavior of 4th generation district heating networks. In contrast with earlier generation networks with a single or few heat sources and pumps, newer installations will prominently feature distributed heat generation units, bringing about a number of challenges for the control and stable operation of these systems, e.g., flow reversals and interactions among pumps controllers, which may lead to severe oscillations. We focus thus on flexible system setups with an arbitrary number of distributed heat sources and end-users interconnected through a meshed, multi-layer distribution network of pipes. Moreover, differently from related works on the topic, we incorporate dynamic models for the pumps in the system and explicitly account for the presence of pressure holding units. By inferring suitable (power-preserving) interconnection ports, we provide a number of claims about the passivity properties of the overall, interconnected system, which proves to be highly beneficial in the design of decentralized control schemes and stability analyses

Cover crops with biofumigation properties for the suppression of plant-parasitic nematodes : a review

The original publication is available at http://www.sawislibrary.co.za/dbtw-wpd/textbase/sajev.htmPlant-parasitic nematodes are a problem in vineyards worldwide, with some species acting as vectors of grapevine soil-transmitted viruses. Global pressure on the use of soil-applied chemical nematicides has led to a search for new control options, or for alternative methods to suppress plant-parasitic nematodes as part of integrated pest management. This paper gives valuable background information on the use of cover crops with biofumigation properties for the suppression of plant-parasitic nematodes in vineyards.Winetech, Dried Fruit Technical Services and the National Research Foundation of South AfricaPublishers' Versio

Novel Bone-Targeting Agent for Enhanced Delivery of Vancomycin to Bone

We examined the pharmacokinetic properties of vancomycin conjugated to a bone-targeting agent (BT) with high affinity for hydroxyapatite after systemic intravenous administration. The results confirm enhanced persistence of BT-vancomycin in plasma and enhanced accumulation in bone relative to vancomycin. This suggests that BT-vancomycin may be a potential carrier for the systemic targeted delivery of vancomycin in the treatment of bone infections, potentially reducing the reliance on surgical debridement to achieve the desired therapeutic outcome

PArallel, Robust, Interface Simulator (PARIS)

Paris (PArallel, Robust, Interface Simulator) is a finite volume code for simulations of immiscible multifluid or multiphase flows. It is based on the "one-fluid" formulation of the Navier-Stokes equations where different fluids are treated as one material with variable properties, and surface tension is added as a singular interface force. The fluid equations are solved on a regular structured staggered grid using an explicit projection method with a first-order or second-order time integration scheme. The interface separating the different fluids is tracked by a Front-Tracking (FT) method, where the interface is represented by connected marker points, or by a Volume-of-Fluid (VOF) method, where the marker function is advected directly on the fixed grid. Paris is written in Fortran95/2002 and parallelized using MPI and domain decomposition. It is based on several earlier FT or VOF codes such as Ftc3D, Surfer or Gerris. These codes and similar ones, as well as Paris, have been used to simulate a wide range of multifluid and multiphase flows

Comparative gender analysis of the efficacy and safety of atazanavir/ritonavir and lopinavir/ritonavir at 96 weeks in the CASTLE study.

OBJECTIVES: To examine whether the overall results of the CASTLE study pertain to both genders, we analysed the efficacy and safety of atazanavir/ritonavir and lopinavir/ritonavir in 277 female and 606 male patients in the open-label, multinational trial over 96 weeks. The trial is registered with ClinicalTrials.gov, number NCT00272779. METHODS: Treatment-naive patients aged ≥ 18 years with HIV-1 RNA ≥ 5000 copies/mL were randomized to receive either atazanavir/ritonavir 300/100 mg once daily or lopinavir/ritonavir 400/100 mg twice daily, with fixed-dose tenofovir/emtricitabine 300/200 mg once daily. RESULTS: At week 96, confirmed virological response rates (HIV RNA \u3c50 copies\u3e/mL; intent-to-treat analysis) were higher in women and men receiving atazanavir/ritonavir than those receiving lopinavir/ritonavir and lower in women than men in both treatment arms (67% of women and 77% of men on atazanavir/ritonavir and 63% of women and 71% of men on lopinavir/ritonavir). These differences were not observed in the on-treatment analysis. Mean change in CD4 cell count from baseline to week 96 was 265 cells/mm(3) for women and 269 cells/mm(3) for men on atazanavir/ritonavir and 298 cells/mm(3) for women and 286 cells/mm(3) for men on lopinavir/ritonavir. Discontinuation rates were higher in women than men in each treatment arm (22% of women and 15% of men on atazanavir/ritonavir and 29% of women and 18% of men on lopinavir/ritonavir). In women and men, grade 2-4 nausea and diarrhoea were more frequent in the lopinavir/ritonavir group; jaundice and hyperbilirubinaemia occurred more frequently in the atazanavir/ritonavir group. CONCLUSIONS: Once-daily atazanavir/ritonavir is an effective and well-tolerated therapeutic option for women and men with HIV-1 infection. The sex-based differences in response may be due to higher discontinuation rates in women

The crystal structure of fac-tricarbonyl(N-benzoylN,N-cyclohexylmethylcarbamimidothioato-k(2)S,O)(pyridine-kN)rhenium(I), C23H24N3O4ReS

Please read abstract in the article.The National Research Foundation of South Africa, Tshwane University of Technology and the University of Pretoria.https://www.degruyter.com/view/j/ncrsChemistr