An Integrated Subharmonic Coupled-Oscillator Scheme for a 60-GHz Phased-Array Transmitter

This paper describes the design of an integrated coupled-oscillator array in SiGe for millimeter-wave applications. The design focuses on a scalable radio architecture where multiple dies are tiled to form larger arrays. A 2 × 2 oscillator array for a 60-GHz transmitter is fabricated with integrated power amplifiers and on-chip antennas. To lock between multiple dies, an injection-locking scheme appropriate for wire-bond interconnects is described. The 2 × 2 array demonstrates a 200–MHz locking range and 1 × 4 array formed by two adjacent chips has a 60-MHz locking range. The phase noise of the coupled oscillators is below 100 dBc/Hz at a 1-MHz offset when locked to an external reference. To the best of the authors’ knowledge, this is the highest frequency demonstration of coupled oscillators fabricated in a conventional silicon integrated-circuit process

Epiphytic bryozoan community of Posidonia oceanica (L.) Delile leaves in two different meadows at disturbed and control locations

The impact of fish farming activities on Posidonia oceanica meadows in the Aegean Sea have been detected by using bryozoan epiphytes as indicators of disturbance. Samples were collected by SCUBA diving in September 2004 for comparing assemblages between disturbed (I1:0-5 m; I2:5-10 m and I3:10-15 m) and control meadows (C1:0-5 m; C2:5-10 m and C3:10-15 m) located at different depths. Regarding to mean percentage cover of bryozoans, significant differences were found between stations, leaf sides, depths and their interactions (p<0.05). Bryozoan species were colonized densely on back side of the adult leaves. Bantariella verticillata, Alcyonidium sp., Aetea truncata, Chorizopora brongniartii, Fenestrulina joannae were frequently observed species on P. oceanica leaves. B. verticillata showed statistically significant side and station differences while other species showed only significant side differences. Moreover, the mean coverage of Aetea truncata showed neither station nor side variations. B. verticillata could be evaluated as an appropriate key species for environmental changes. In the impacted meadow, higher mean coverage values of the species were particularly determined on front side of the leaves. These results suggest that characteristics of localities, leaf sides and leaf parts can be responsible factors on coverage value of epiphytic bryozoan species

Constructal design in the cooling and hydraulic performance of tube heat sinks

Liquid-cooled hot plates require effective thermal management which can be accomplished by implementing appropriate cooling architectures. This investigation is about high heat-generating systems and reports the performance of heated plates with various cooling flow configurations: Serpentine flow, parallel tubes flow, and two tree-shape flow systems. Single and double objectives with size constraint are studied to obtain the best design. The influence of fluid inlet position is also studied. The results are presented in terms of hydraulic and thermal characteristics for plates that is subject to a constant heat flux, and contain tubes with fixed total lateral area for cooling. A 3D numerical study is conducted to analyze the performance of these systems for Reynolds numbers ranging from 1000 to 33,000. The results obtained include temperatures of the plate, uniformity of temperature of the plate, fluid flow resistance and heat dissipation. Dimensionless parameters are identified to characterize the thermal performance, hydraulic performance, and hydrothermal performance as a function of the Reynolds number. The results show that a tree-shaped flow network of tubes inserted in the plate with inlet placed at the center of the plate presents the best cooling performance, with more cooling capacity and less flow resistance (and pumping power)

Analysis of loop heat pipe performance under varying wick load

Loop heat pipes (LHP) are heat transfer devices used to enhance cooling of small spaces and basically consist of sealed tubes connecting a heat source, the evaporator, whose major part is a porous wick, with a condenser that operates as heat sink. In this paper we analyse the effect of curvature of the liquid vapor interface upon the vapor pressure within wick pores. We show how this effect affects start-up by requiring a difference between wick and condenser temperatures as higher as wick pore width becomes smaller. We analysed also transient operation and found that idealy LHP are self-adjusting systems that tend to stable operation. We present a formula to describe the transient regime. The analysis provides also optimization of wick pore width for maximum heat transfer. Optimal pore width is shown to vary with temperature difference between wick and condenser. It is envisaged how this feature may help in LHP design

Numerical Particle Transport in Partitioned Room.

In this work, we solved particle transport in a two-zone enclosure numerically with different airflow pattems, particle properties and algo source positions. A discrete trajectory was employed for the particIe movement. Five isotropic line sources which are alI taken at different positions oftne same zone were festejo It was observed that for alI airflow pattems, residence time increases with decreasing size of particIes. Increase in size and mass increases the chaTIceof particles to get deposited auto the fIoor. Source locations should be chosen in the main stream of the fIow so that particles convect fast through and not contribute indoor polIutant concentration. ConcIusions were drawn for every numerical experiment in arder to show tendencies of particle dynamics within the encIosure

Pion wave functions from holographic QCD and the role of infrared renormalons in photon-photon collisions

In this article, we calculate the contribution of the higher-twist Feynman diagrams to the large-$p_T$ inclusive single pion production cross section in photon-photon collisions in case of the running coupling and frozen coupling approaches within holographic QCD. We compare the resummed higher-twist cross sections with the ones obtained in the framework of the frozen coupling approach and leading-twist cross section. Also, we show that in the context of frozen coupling approach a higher-twist contribution to the photon-photon collisions cross section is normalized in terms of the pion electromagnetic form factor.Comment: 21 pages, 15 figures. arXiv admin note: text overlap with arXiv:0709.2072 by other author

Influence of flow with suspended particles on temperature fields and convective heat transfer

The present paper reports the results of a numerical study of forced convection heat transfer between two plates filled with particles. We study the influence of particles suspended in flows on heat transfer enhancement. We consider steady-state fluid flow between two flat horizontal parallel plates with both plates kept at the same temperature. Mono-disperse particles with low and high thermal conductivities injected at the entrance are entrained with the flow. Their effects on temperature field and convective heat transfer are determined from the flow field

Utjecaj oligosaharida hitozana na određene hematološke pokazatelje u štakora izloženih kadmiju

The aim of the study was to investigate the effects of chitosan oligosaccharide (COS) on some hematological parameters, and define the percentage of alpha-naphthyl acetate esterase (ANAE) positive lymphocytes in rats that had been exposed to cadmium (Cd). Thirty-two (n = 32) male Wistar albino rats were randomly divided into four groups as the control (C), chitosan oligosaccharide (COS), cadmium (Cd), and Cd + COS (CdCOS) groups. Blood samples were collected to assess erythrocytes (RBC), leukocytes (WBC), hemoglobin levels (HGB), hematocrit values (HCT), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), mean corpuscular volume (MCV), platelets (PLT), and alpha-naphthyl acetate esterase (ANAE) positive lymphocytes. The number of WBCs significantly increased in the Cd group compared to the C, CdCOS, and COS groups (P<0.05). Although the lymphocyte count decreased significantly in the Cd group (P<0.05), it was ameliorated by COS treatment in the CdCOS group compared to the Cd group (P<0.05). Also, the percentage of peripheral blood ANAE positive lymphocytes decreased significantly in the CdCOS and Cd groups (P<0.05). COS exhibits a partially protective effect on some hematological characteristics, apart from the percentage of ANAE positive lymphocyte in cases of chronic Cd exposure.Cilj ovog rada bio je istražiti učinak oligosaharida hitozana (COS) na određene hematološke pokazatelje odnosno postotak limfocita pozitivnih na alfa-naftil-acetat-esterazu (ANAE) u štakora izloženih kadmiju (Cd). Mužjaci (n = 32) pasmine Wistar albino, slučajnim odabirom podijeljeni su u četiri skupine: kontrolnu (C), skupinu s oligosaharidom hitozanom (COS), skupinu s kadmijem (Cd) i skupinu s kadmijem i oligosaharidom hitozanom (CdCOS). Prikupljeni su uzorci krvi kako bi se odredili eritrociti (RBC), leukociti (WBC), hemoglobin (HGB), hematokrit (HCT), prosječni hemoglobin u eritrocitima (MCH) i njegova koncentracija (MCHC), prosječan obujam eritrocita (MCV), trombociti (PLT), te limfociti pozitivni na alfa-naftil-acetat-esterazu (ANAE). Broj leukocita znakovito je porastao u skupini Cd u usporedbi s kontrolnom skupinom te skupinama C, CdCOS, i COS (P < 0,05). Iako je broj limfocita znakovito smanjen u skupini Cd (P < 0,05), to je ublaženo primjenom COS-a u skupini CdCOS u usporedbi sa skupinom Cd (P < 0,05). Također, postotak limfocita iz periferne krvi pozitivnih na ANAE znakovito je smanjen u skupinama CdCOS i Cd (P < 0,05). COS je, u slučaju kronične izloženosti štakora kadmiju, pokazao djelomice zaštitni učinak na određene hematološke značajke, osim na postotak limfocita pozitivnih na ANAE

Airborne Pathogens Transport in an Aircraft Cabin

Airborne pathogens can spread within an aircraft cabin from sneezing, coughing or breathing of a sick passenger. This paper reports a 3D numerical study on the transport of airborne pathogens inside Boeing 767 cabin. After cough or sneeze of an infected passenger, the entire unsteady pathogen dispersion process is simulated. Effects under study include the direction of coughing on the pathogens propagation and the spreading times from infected to hosts passengers

Quadrature Subharmonic Coupled Oscillators for a 60GHz SiGe Scalable Phased Array

This paper describes an integrated coupled oscillator array in SiGe for millimeter wave applications. The design focuses on scalable radio architectures where multiple dies are tiled to form larger arrays. A 2 x 2 oscillator array for a 60GHz transmitter is designed with integrated power amplifiers and antennas. The 2 x 2 array demonstrates a 200MHz locking range and 1 x 4 array formed by two adjacent chips has a 60MHz locking range. The phase noise of the array is below -110dBc/Hz at a 1MHz offset