Modeling of a Hot Gas Bypass Test Block for Centrifugal Compressors

The increasingly competitive building equipment and control industry pushes manufacturers to devote more resources each year to research and development, continually improving the performance and efficiency of their products to develop and maintain a competitive edge. Compressor development is an expensive endeavor because of prototyping and testing costs, but the cost and time required for testing can be minimized by developing a model of the compressor test block to predict its behavior with a given prototype compressor at specified operating conditions. This paper presents a thermodynamic model of a hot gas bypass test block used to evaluate centrifugal compressor performance at a compressor development facility. The test block uses cooling towers to reject the heat of compression to outdoor air, and experience has shown that the range of achievable compressor test conditions can be limited by outdoor air temperature and humidity, which control the heat rejection rate. Therefore, one goal of the model development was to provide a means for evaluating the feasibility of tests at given ambient conditions. By incorporating models of the cooling towers into the test block model, test operators now are able to predict the range of compressor suction and discharge conditions that can be tested under the current outdoor air conditions. A second goal of the model was to assist in selecting the orifice plate used in the orifice flow meter that measures mass flow through the compressor. Operators previously had to make an educated guess as to the best orifice plate size in advance of running the tests, but the model now identifies the orifice diameters that result in pressure drops within the desired range, minimizing the trial and error involved in testing. The model assumes that the system operates at steady-state conditions and uses a compressor map to model expected prototype compressor performance. Therefore, this paper focuses on the condenser and cooling tower models, which are the most important elements for predicting the impact of outdoor conditions on cycle performance. It is shown that the resulting model achieves reasonable agreement with experimental data and provides a useful orifice selection routine

Phloem sap and leaf δ13C, carbohydrates, and amino acid concentrations in Eucalyptus globulus change systematically according to flooding and water deficit treatment

Phloem is a central conduit for the distribution of photoassimilate, nutrients, and signals among plant organs. A revised technique was used to collect phloem sap from small woody plants in order to assess changes in composition induced by water deficit and flooding. Bled phloem sap δ13C and sugar concentrations were compared to δ13C of bulk material, soluble carbon extracts, and the neutral sugar fraction from leaves. Amino acid composition and inorganic ions of the phloem sap was also analysed. Quantitative, systematic changes were detected in phloem sap composition and δ13C in response to altered water availability. Phloem sap δ13C was more sensitive to changes of water availability than the δ13C of bulk leaf, the soluble carbon fraction, and the neutral soluble fraction of leaves. Changes in water availability also resulted in significant changes in phloem sugar (sucrose and raffinose), inorganic nutrient (potassium), and amino acid (phenylalanine) concentrations with important implications for the maintenance of phloem function and biomass partitioning. The differences in carbohydrate and amino acid composition as well as the δ13C in the phloem, along with a new model system for phloem research, offer an improved understanding of the phloem-mediated signal, nutrient, and photoassimilate transduction in relation to water availability

Larvicidal, antimicrobial and brine shrimp activities of extracts from Cissampelos mucronata and Tephrosia villosa from coast region, Tanzania

<p>Abstract</p> <p>Background</p> <p>The leaves and roots of <it>Cissampelos mucronata </it>A. Rich (Menispermaceae) are widely used in the tropics and subtropics to manage various ailments such as gastro-intestinal complaints, menstrual problems, venereal diseases and malaria. In the Coast region, Tanzania, roots are used to treat wounds due to extraction of jigger. Leaves of <it>Tephrosia villosa </it>(L) Pers (Leguminosae) are reported to be used in the treatment of diabetes mellitus in India. In this study, extracts from the roots and aerial parts of <it>C. mucronata </it>and extracts from leaves, fruits, twigs and roots of <it>T. villosa </it>were evaluated for larvicidal activity, brine shrimps toxicity and antimicrobial activity.</p> <p>Methods</p> <p>Powdered materials from <it>C. mucronata </it>were extracted sequentially by dichloromethane followed by ethanol while materials from <it>T.villosa </it>were extracted by ethanol only. The extracts obtained were evaluated for larvicidal activity using <it>Culex quinquefasciatus </it>Say larvae, cytotoxicity using brine shrimp larvae and antimicrobial activity using bacteria and fungi.</p> <p>Results</p> <p>Extracts from aerial parts of <it>C. Mucronata </it>exhibited antibacterial activity against <it>Staphylococcus aureus</it>, <it>Escherichia coli</it>, <it>Pseudomonas aeruginosa</it>, <it>Salmonella typhi</it>, <it>Vibrio cholera</it>, <it>Bacillus anthracis</it>, <it>Streptococcus faecalis </it>and antifungal activity against <it>Candida albicans </it>and <it>Cryptococcus neoformans</it>. They exhibited very low toxicity to brine shrimps and had no larvicidal activity. The root extracts exhibited good larvicidal activity but weak antimicrobial activity. The root dichloromethane extracts from <it>C. mucronata </it>was found to be more toxic with an LC₅₀value of 59.608 μg/mL while ethanolic extracts from root were not toxic with LC₅₀>100 μg/mL). Ethanol extracts from fruits and roots of <it>T. villosa </it>were found to be very toxic with LC₅₀values of 9.690 μg/mL and 4.511 μg/mL, respectively, while, ethanol extracts from leaves and twigs of <it>T. villosa </it>were found to be non toxic (LC₅₀>100 μg/mL).</p> <p>Conclusion</p> <p>These results support the use of <it>C. mucronata </it>in traditional medicine for treatment of wounds. Extracts of <it>C. mucronata </it>have potential to yield active antimicrobial and larvicidal compounds. The high brine shrimp toxicity of <it>T. villosa </it>corroborates with literature reports that the plant is toxic to both livestock and fish. The results further suggest that <it>T. villosa </it>extracts have potential to yield larvicidal and possibly cytotoxic compounds. Further studies to investigate the bioactive compounds responsible for the observed biological effects are suggested.</p

Use of beneficial bacteria and their secondary metabolites to control grapevine pathogen diseases

Grapevine is one of the most important economic crops yielding berries, wine products as well as derivates. However, due to the large array of pathogens inducing diseases on this plant, considerable amounts of pesticides—with possible negative impact on the environment and health—have been used and are currently used in viticulture. To avoid negative impacts of such products and to ensure product quality, a substantial fraction of pesticides needs to be replaced in the near future. One solution can be related to the use of beneficial bacteria inhabiting the rhizo- and/or the endosphere of plants. These biocontrol bacteria and their secondary metabolites can reduce directly or indirectly pathogen diseases by affecting pathogen performance by antibiosis, competition for niches and nutrients, interference with pathogen signaling or by stimulation of host plant defenses. Due to the large demand for biocontrol of grapevine diseases, such biopesticides, their modes of actions and putative consequences of their uses need to be described. Moreover, the current knowledge on new strains from the rhizo- and endosphere and their metabolites that can be used on grapevine plants to counteract pathogen attack needs to be discussed. This is in particular with regard to the control of root rot, grey mould, trunk diseases, powdery and downy mildews, pierce’s disease, grapevine yellows as well as crown gall. Future prospects on specific beneficial microbes and their secondary metabolites that can be used as elicitors of plant defenses and/or as biocontrol agents with potential use in a more sustainable viticulture will be further discussed

Belle II Vertex Detector Performance

The Belle II experiment at the SuperKEKB accelerator (KEK, Tsukuba, Japan) collected its first e+e− collision data in the spring 2019. The aim of accumulating a 50 times larger data sample than Belle at KEKB, a first generation B-Factory, presents substantial challenges to both the collider and the detector, requiring not only state-of-the-art hardware, but also modern software algorithms for tracking and alignment. The broad physics program requires excellent performance of the vertex detector, which is composed of two layers of DEPFET pixels and four layers of double sided-strip sensors. In this contribution, an overview of the vertex detector of Belle II and our methods to ensure its optimal performance, are described, and the first results and experiences from the first physics run are presented

Search for Axionlike Particles Produced in e⁺ e⁻ Collisions at Belle II

International audienceWe present a search for the direct production of a light pseudoscalar a decaying into two photons with the Belle II detector at the SuperKEKB collider. We search for the process e+e-→γa, a→γγ in the mass range 0.2

Search for Axionlike Particles Produced in e+e- Collisions at Belle II

We present a search for the direct production of a light pseudoscalar a decaying into two photons with the Belle II detector at the SuperKEKB collider. We search for the process e+e-→γa, a→γγ in the mass range 0.2<9.7 GeV/c2 using data corresponding to an integrated luminosity of (445±3) pb-1. Light pseudoscalars interacting predominantly with standard model gauge bosons (so-called axionlike particles or ALPs) are frequently postulated in extensions of the standard model. We find no evidence for ALPs and set 95% confidence level upper limits on the coupling strength gaγγ of ALPs to photons at the level of 10-3 GeV-1. The limits are the most restrictive to date for 0.2<1 GeV/c2

Alignment of the CMS silicon tracker during commissioning with cosmic rays

This is the Pre-print version of the Article. The official published version of the Paper can be accessed from the link below - Copyright @ 2010 IOPThe CMS silicon tracker, consisting of 1440 silicon pixel and 15 148 silicon strip detector modules, has been aligned using more than three million cosmic ray charged particles, with additional information from optical surveys. The positions of the modules were determined with respect to cosmic ray trajectories to an average precision of 3–4 microns RMS in the barrel and 3–14 microns RMS in the endcap in the most sensitive coordinate. The results have been validated by several studies, including laser beam cross-checks, track fit self-consistency, track residuals in overlapping module regions, and track parameter resolution, and are compared with predictions obtained from simulation. Correlated systematic effects have been investigated. The track parameter resolutions obtained with this alignment are close to the design performance.This work is supported by FMSR (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES (Croatia); RPF (Cyprus); Academy of Sciences and NICPB (Estonia); Academy of Finland, ME, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF (Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico); PAEC (Pakistan); SCSR (Poland); FCT (Portugal); JINR (Armenia, Belarus, Georgia, Ukraine, Uzbekistan); MST and MAE (Russia); MSTDS (Serbia); MICINN and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); TUBITAK and TAEK (Turkey); STFC (United Kingdom); DOE and NSF (USA)

Commissioning and performance of the CMS pixel tracker with cosmic ray muons

This is the Pre-print version of the Article. The official published verion of the Paper can be accessed from the link below - Copyright @ 2010 IOPThe pixel detector of the Compact Muon Solenoid experiment consists of three barrel layers and two disks for each endcap. The detector was installed in summer 2008, commissioned with charge injections, and operated in the 3.8 T magnetic field during cosmic ray data taking. This paper reports on the first running experience and presents results on the pixel tracker performance, which are found to be in line with the design specifications of this detector. The transverse impact parameter resolution measured in a sample of high momentum muons is 18 microns.This work is supported by FMSR (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES (Croatia); RPF (Cyprus); Academy of Sciences and NICPB (Estonia); Academy of Finland, ME, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF (Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico); PAEC (Pakistan); SCSR (Poland); FCT (Portugal); JINR (Armenia, Belarus, Georgia, Ukraine, Uzbekistan); MST and MAE (Russia); MSTDS (Serbia); MICINN and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); TUBITAK and TAEK (Turkey); STFC (United Kingdom); DOE and NSF (USA)