Design of a CO2 heat pump drier with dynamic modelling tools

Drying is an energy and time intensive process which thermal energy demand is mostly provided by fossil resources. Especially in the food processing industry it is important to increase the energy efficiency of drying processes in terms of organic products and sustainability. The potential of using a heat pump with R744 (CO2) as a working media to provide the thermal energy was investigated for typical food drying temperature of 50 °C at a relative humidity of 20 %. A dynamic heat pumpassisted dryer model has been developed and validated. The model was created with respect to heat transfer, pressure loss and flow requirements. The simulated results showed that a closed-loop heat pump assisted drying process has the potential to reduce the energy demand by around 80 % compared to conventional open-loop drying processes with fossil resources as energy source. Furthermore, the implementation of a bypass in the air cycle was examined to further enhance the energy efficiency of the system

OH (1720 MHz) Masers: A Multiwavelength Study of the Interaction between the W51C Supernova Remnant and the W51B Star Forming Region

We present a comprehensive view of the W51B HII region complex and the W51C supernova remnant (SNR) using new radio observations from the VLA, VLBA, MERLIN, JCMT, and CSO along with archival data from Spitzer, ROSAT, ASCA, and Chandra. Our VLA data include the first 400 cm (74 MHz) continuum image of W51 at high resolution (88 arcsec). The 400 cm image shows non-thermal emission surrounding the G49.2-0.3 HII region, and a compact source of non-thermal emission (W51B_NT) coincident with the previously-identified OH (1720 MHz) maser spots, non-thermal 21 and 90 cm emission, and a hard X-ray source. W51B_NT falls within the region of high likelihood for the position of TeV gamma-ray emission. Using the VLBA three OH (1720 MHz) maser spots are detected in the vicinity of W51B_NT with sizes of 60 to 300 AU and Zeeman effect magnetic field strengths of 1.5 to 2.2 mG. The multiwavelength data demonstrate that the northern end of the W51B HII region complex has been partly enveloped by the advancing W51C SNR and this interaction explains the presence of W51B_NT and the OH masers. This interaction also appears in the thermal molecular gas which partially encircles W51B_NT and exhibits narrow pre-shock (DeltaV 5 km/s) and broad post-shock (DeltaV 20 km/s) velocity components. RADEX radiative transfer modeling of these two components yield physical conditions consistent with the passage of a non-dissociative C-type shock. Confirmation of the W51B/W51C interaction provides additional evidence in favor of this region being one of the best candidates for hadronic particle acceleration known thus far.Comment: Accepted to Ap

The Nature of the Nuclear H2O Masers of NGC 1068: Reverberation and Evidence for a Rotating Disk Geometry

We report new (1995) Very Large Array observations and (1984 - 1999) Effelsberg 100m monitoring observations of the 22 GHz H2O maser spectrum of the Seyfert 2 galaxy NGC 1068. The sensitive VLA observations provide a registration of the 22 GHz continuum emission and the location of the maser spots with an accuracy of ~ 5 mas. Within the monitoring data, we find evidence that the nuclear masers vary coherently on time-scales of months to years, much more rapidly than the dynamical time-scale. We argue that the nuclear masers are responding in reverberation to a central power source, presumably the central engine. Between October and November 1997, we detected a simultaneous flare of the blue-shifted and red-shifted satellite maser lines. Reverberation in a rotating disk naturally explains the simultaneous flaring. There is also evidence that near-infrared emission from dust grains associated with the maser disk also responds to the central engine. We present a model in which an X-ray flare results in both the loss of maser signal in 1990 and the peak of the near-infrared light curve in 1994. In support of a rotating disk geometry for the nuclear masers, we find no evidence for centripetal accelerations of the redshifted nuclear masers; the limits are +/- 0.006 km/s/year, implying that the masers are located within 2 degrees of the kinematic line-of-nodes. We also searched for high velocity maser emission like that observed in NGC 4258. In both VLA and Effelsberg spectra, we detect no high velocity lines between +/- 350 km/s to +/- 850 km/s relative to systemic, arguing that masers only lie outside a radius of ~ 0.6 pc (1.9 light years) from the central engine (assuming a distance of 14.4 Mpc).Comment: 62 pages, 19 figure

Ultrasound-assisted drying of orange peel in atmospheric freeze-dryer and convective dryer operated at moderate temperature

This is an Author's Accepted Manuscript of an article published in Ronaldo E. Mello, Alessia Fontana, Antonio Mulet, Jefferson Luiz, G. Correa & Juan A. Cárcel (2020) Ultrasound-assisted drying of orange peel in atmospheric freeze-dryer and convective dryer operated at moderate temperature, Drying Technology, 38:1-2, 259-267, DOI: 10.1080/07373937.2019.1645685 [copyright Taylor & Francis], available online at: http://www.tandfonline.com/10.1080/07373937.2019.1645685[EN] Atmospheric freeze-drying (AFD) at -10 degrees C and moderate temperature convective drying (MTD) at 50 degrees C without and with ultrasound application (20.5 kW/m(3)) were carried out. Alcohol insoluble residue (AIR) and its swelling capacity (SC), water retention capacity (WRC) and fat retention capacity (FRC) were measured in the dried product. Ultrasound significantly shortened the drying time in both processes, the intensification effect being more significant in atmospheric freeze-drying (57% and 27% reduction in atmospheric freeze-drying and convective drying, respectively). As regards AIR and WRC, no effect was observed of either the drying temperature or ultrasound application. On the contrary, SC was significantly lower in AFD samples. The FRC of MTD samples was similar to that of the fresh ones and higher than the values obtained for atmospheric freeze-dried samples. Therefore, convective drying at moderate temperature preserved the AIR properties better than atmospheric freeze-drying.The authors acknowledge the financial support of INIA-ERDF through project RTA2015-00060-C04-02. We are also grateful for the economic support of the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior - Brasil (Capes)- Finance Code 001, Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq) and Fundacao de Amparo a Pesquisa de Minas Gerais (FAPEMIG).Mello, RE.; Fontana, A.; Mulet Pons, A.; Correa, J.; Carcel, JA. (2020). Ultrasound-assisted drying of orange peel in atmospheric freeze-dryer and convective dryer operated at moderate temperature. Drying Technology. 38(1-2):259-267. https://doi.org/10.1080/07373937.2019.1645685S259267381-2Freire, F. B., Atxutegi, A., Freire, F. B., Freire, J. T., Aguado, R., & Olazar, M. (2016). An adaptive lumped parameter cascade model for orange juice solid waste drying in spouted bed. Drying Technology, 35(5), 577-584. doi:10.1080/07373937.2016.1190937Tasirin, S. M., Puspasari, I., Sahalan, A. Z., Mokhtar, M., Ghani, M. K. A., & Yaakob, Z. (2014). Drying ofCitrus sinensisPeels in an Inert Fluidized Bed: Kinetics, Microbiological Activity, Vitamin C, and Limonene Determination. Drying Technology, 32(5), 497-508. doi:10.1080/07373937.2013.838782Zielinska, M., Sadowski, P., & Błaszczak, W. (2015). Combined hot air convective drying and microwave-vacuum drying of blueberries (Vaccinium corymbosumL.): Drying kinetics and quality characteristics. Drying Technology, 34(6), 665-684. doi:10.1080/07373937.2015.1070358Moreno, C., Brines, C., Mulet, A., Rosselló, C., & Cárcel, J. A. (2017). Antioxidant potential of atmospheric freeze-dried apples as affected by ultrasound application and sample surface. Drying Technology, 35(8), 957-968. doi:10.1080/07373937.2016.1256890Garcia-Perez, J. V., Ortuño, C., Puig, A., Carcel, J. A., & Perez-Munuera, I. (2011). Enhancement of Water Transport and Microstructural Changes Induced by High-Intensity Ultrasound Application on Orange Peel Drying. Food and Bioprocess Technology, 5(6), 2256-2265. doi:10.1007/s11947-011-0645-0Do Nascimento, E. M. G. C., Mulet, A., Ascheri, J. L. R., de Carvalho, C. W. P., & Cárcel, J. A. (2016). Effects of high-intensity ultrasound on drying kinetics and antioxidant properties of passion fruit peel. Journal of Food Engineering, 170, 108-118. doi:10.1016/j.jfoodeng.2015.09.015Martins, M. P., Cortés, E. J., Eim, V., Mulet, A., & Cárcel, J. A. (2018). Stabilization of apple peel by drying. Influence of temperature and ultrasound application on drying kinetics and product quality. Drying Technology, 37(5), 559-568. doi:10.1080/07373937.2018.1474476García-Pérez, J. V., Cárcel, J. A., Riera, E., & Mulet, A. (2009). Influence of the Applied Acoustic Energy on the Drying of Carrots and Lemon Peel. Drying Technology, 27(2), 281-287. doi:10.1080/07373930802606428Blasco, M., García-Pérez, J. V., Bon, J., Carreres, J. E., & Mulet, A. (2006). Effect of Blanching and Air Flow Rate on Turmeric Drying. Food Science and Technology International, 12(4), 315-323. doi:10.1177/1082013206067352Garau, M. C., Simal, S., Femenia, A., & Rosselló, C. (2006). Drying of orange skin: drying kinetics modelling and functional properties. Journal of Food Engineering, 75(2), 288-295. doi:10.1016/j.jfoodeng.2005.04.017Garau, M. C., Simal, S., Rosselló, C., & Femenia, A. (2007). Effect of air-drying temperature on physico-chemical properties of dietary fibre and antioxidant capacity of orange (Citrus aurantium v. Canoneta) by-products. Food Chemistry, 104(3), 1014-1024. doi:10.1016/j.foodchem.2007.01.009Beigi, M. (2015). Hot air drying of apple slices: dehydration characteristics and quality assessment. Heat and Mass Transfer, 52(8), 1435-1442. doi:10.1007/s00231-015-1646-8Santos, P. H. S., & Silva, M. A. (2008). Retention of Vitamin C in Drying Processes of Fruits and Vegetables—A Review. Drying Technology, 26(12), 1421-1437. doi:10.1080/07373930802458911Gallego-Juárez, J. A., Riera, E., de la Fuente Blanco, S., Rodríguez-Corral, G., Acosta-Aparicio, V. M., & Blanco, A. (2007). Application of High-Power Ultrasound for Dehydration of Vegetables: Processes and Devices. Drying Technology, 25(11), 1893-1901. doi:10.1080/07373930701677371Santacatalina, J. V., Ahmad-Qasem, M. H., Barrajón-Catalán, E., Micol, V., García-Pérez, J. V., & Cárcel, J. A. (2014). Use of Novel Drying Technologies to Improve the Retention of Infused Olive Leaf Polyphenols. Drying Technology, 33(9), 1051-1060. doi:10.1080/07373937.2014.982251Silva, V. M., & Viotto, L. A. (2010). Drying of sicilian lemon residue: influence of process variables on the evaluation of the dietary fiber produced. Ciência e Tecnologia de Alimentos, 30(2), 421-428. doi:10.1590/s0101-20612010000200020Garcia-Amezquita, L. E., Tejada-Ortigoza, V., Campanella, O. H., & Welti-Chanes, J. (2018). Influence of Drying Method on the Composition, Physicochemical Properties, and Prebiotic Potential of Dietary Fibre Concentrates from Fruit Peels. Journal of Food Quality, 2018, 1-11. doi:10.1155/2018/9105237Abou-Arab, E. A., Mahmoud, M. H., & Abu-Salem, F. M. (2017). Functional Properties of Citrus Peel as Affected by Drying Methods. American Journal of Food Technology, 12(3), 193-200. doi:10.3923/ajft.2017.193.200Ghanem Romdhane, N., Bonazzi, C., Kechaou, N., & Mihoubi, N. B. (2015). Effect of Air-Drying Temperature on Kinetics of Quality Attributes of Lemon (Citrus limoncv. lunari) Peels. Drying Technology, 33(13), 1581-1589. doi:10.1080/07373937.2015.101226

Observational Evidence for Massive Black Holes in the Centers of Active Galaxies

Naturally occurring water vapor maser emission at 1.35 cm wavelength provides an accurate probe for the study of accretion disks around highly compact objects, thought to be black holes, in the centers of active galaxies. Because of the exceptionally fine angular resolution, 200 microarcseconds, obtainable with very long baseline interferometry, accompanied by high spectral resolution, < 0.1 km/s, the dynamics and structures of these disks can be probed with exceptional clarity. The data on the galaxy NGC4258 are discussed here in detail. The mass of the black hole binding the accretion disk is 3.9 times 10^7 solar masses. Although the accretion disk has a rotational period of about 800 years, the physical motions of the masers have been directly measured with VLBI over a period of a few years. These measurements also allow the distance from the earth to the black hole to be estimated to an accuracy of 4 percent. The status of the search for other maser/black hole candidates is also discussed.Comment: 24 pages, 11 figures, latex, uses aaspp4 style file. To be published in the Journal of Astronomy and Astrophysics (India), proceedings of the Discussion Meeting on the Physics of Black Holes, Bangalore, India: December 199

Discrete Source Survey of 6 GHz OH emission from PNe & pPNe and first 6 GHz images of K 3-35

The aim of this study is to investigate the physical properties of molecular envelopes of planetary nebulae in their earliest stages of evolution. Using the 100m telescope at Effelsberg, we have undertaken a high sensitivity discrete source survey for the first excited state of OH maser emission (J=5/2, 2PI3/2 at 6GHz) in the direction of planetary and proto-planetary nebulae exhibiting 18cm OH emission (main and/or satellite lines), and we further validate our detections using the Nan\c{c}ay radio telescope at 1.6-1.7GHz and MERLIN interferometer at 1.6-1.7 and 6GHz. Two sources have been detected at 6035MHz (5cm), both of them are young (or very young) planetary nebulae. The first one is a confirmation of the detection of a weak 6035MHz line in Vy 2-2. The second one is a new detection, in K 3-35, which was already known to be an exceptional late type star because it exhibits 1720MHz OH emission. The detection of 6035MHz OH maser emission is confirmed by subsequent observations made with the MERLIN interferometer. These lines are very rarely found in evolved stars. The 1612MHz masers surround but are offset from the 1720 and 6035MHz masers which in turn lie close to a compact 22GHz continuum source embedded in the optical nebula.Comment: 9 pages, 7 figures, published in A&

The Shroud Around the Twin Radio Jets in NGC 1052

(Abridged) We discuss multiple VLBI continuum and spectral line observations and WSRT spectroscopy of NGC 1052. Sub-parsec scale features move outward at approximately 0.26c in bi-symmetric jets, most likely oriented near the plane of the sky. Absorption and emission signatures reveal ionised, atomic, and molecular components of the surrounding medium. Seven-frequency (1.4 to 43 GHz) VLBA observations show free-free absorption in the inner parsec, probably together with synchrotron self-absorption. There is apparently a geometrically thick but patchy structure oriented roughly orthogonal to the jets. The western jet is receding: it is covered more deeply and extensively. HI spectral line VLBI reveals atomic gas in front of both jets. There appear to be three velocity systems. The deepest, at "high velocities" (receding by 125 to 200 km/s), seems restricted to a shell 1 to 2 pc away from the core, within which this gas might be largely ionised. WSRT spectroscopy has revealed 1667 and 1665 MHz OH absorption with their line ratio varying roughly from 1:1 to 2:1 between -35 and 200 km/s. In the high velocity system the OH profiles are similar to HI, suggesting co-location of that atomic and molecular gas, and leaving unclear the connection to the H2O masing gas seen elsewhere. We have also detected both 18cm OH satellite lines in the high velocity system. They have conjugate profiles: 1612 MHz is in absorption, and 1720 MHz in emission.Comment: 16 pages, 14 figures, LaTeX, includes aa.cls, accepted for publication in Astronomy and Astrophysic

The Caltech Millimeter Wave Interferometer

The Caltech Millimeter-Wave Interferometer has recently begun observations at a wavelength of 2.6 mm. We describe the instrument and some of the first results from it

Protein interactions in Xenopus germ plasm RNP particles

Hermes is an RNA-binding protein that we have previously reported to be found in the ribonucleoprotein (RNP) particles of Xenopus germ plasm, where it is associated with various RNAs, including that encoding the germ line determinant Nanos1. To further define the composition of these RNPs, we performed a screen for Hermes-binding partners using the yeast two-hybrid system. We have identified and validated four proteins that interact with Hermes in germ plasm: two isoforms of Xvelo1 (a homologue of zebrafish Bucky ball) and Rbm24b and Rbm42b, both RNA-binding proteins containing the RRM motif. GFP-Xvelo fusion proteins and their endogenous counterparts, identified with antisera, were found to localize with Hermes in the germ plasm particles of large oocytes and eggs. Only the larger Xvelo isoform was naturally found in the Balbiani body of previtellogenic oocytes. Bimolecular fluorescence complementation (BiFC) experiments confirmed that Hermes and the Xvelo variants interact in germ plasm, as do Rbm24b and 42b. Depletion of the shorter Xvelo variant with antisense oligonucleotides caused a decrease in the size of germ plasm aggregates and loosening of associated mitochondria from these structures. This suggests that the short Xvelo variant, or less likely its RNA, has a role in organizing and maintaining the integrity of germ plasm in Xenopus oocytes. While GFP fusion proteins for Rbm24b and 42b did not localize into germ plasm as specifically as Hermes or Xvelo, BiFC analysis indicated that both interact with Hermes in germ plasm RNPs. They are very stable in the face of RNA depletion, but additive effects of combinations of antisense oligos suggest they may have a role in germ plasm structure and may influence the ability of Hermes protein to effectively enter RNP particles

A decentralized spectrum allocation and partitioning scheme for a two-tier macro-femtocell network with downlink beamforming

This article examines spectrum allocation and partitioning schemes to mitigate cross-tier interference under downlink beamforming environments. The enhanced SIR owing to beamforming allows more femtocells to share their spectrum with the macrocell and accordingly improves overall spectrum efficiency. We first design a simplified centralized scheme as the optimum and then propose a practical decentralized algorithm that determines which femtocells to use the full or partitioned spectrum with acceptable control overhead. To exploit limited information of the received signal strength efficiently, we consider two types of probabilistic femtocell base station (HeNB) selection policies. They are equal selection and interference weighted selection policies, and we drive their outage probabilities for a macrocell user. Through performance evaluation, we demonstrate that the outage probability and the cell capacity in our decentralized scheme are significantly better than those in a conventional cochannel deployment scheme. Furthermore, we show that the cell utility in our proposed scheme is close to that in the centralized scheme and better than that in the spectrum partitioning scheme with a fixed ratio.open0