Flat Lid Research Articles

Effect of thermal radiation and inclined magnetic field on thermosolutal mixed convection in a partially active wavy trapezoidal enclosure filled with hybrid nanofluid

This work focuses on the examination of the magneto-thermosolutal convection in a lid-driven wavy trapezoidal enclosure in the presence of thermal radiation. The wavy cavity is filled with radiative Fe3O4-Cu-H2O hybrid nanoliquid. In this work, two cases are considered depending on the location of heat and concentration sources. A portion of the vertical walls are kept hot and in high concentration while the remaining parts are in adiabatic condition. The adiabatic flat upper lid is moving towards the right with equal speed. In addition, the lower wavy border is cold and low concentration. The governing Navier–Stokes equations are modeled to describe thermosolutal phenomena within the wavy enclosure. These equations are solved by reconstructing a recently developed compact scheme. Computed outcomes are presented in terms of streamlines, isotherms, iso-concentrations, average Nusselt and Sherwood numbers to evoke the thermosolutal phenomena for various physical parameters. Also, computing in-house code is validated with the published numerical and experimental and literatures. This investigation surveys the roles of several well-defined parameters such as Richardson number (Ri), Lewis number (Le), Buoyancy ratio number (N), Radiation parameter (Rd), Hartmann number (Ha), inclination of angle (γ), undulation of the wavy surface (d) and solid volume fraction (ϕhnp) of the hybrid nanofluid. An increase in the Lewis number (Le) enhances species diffusion within the system but diminishes thermal transport. This work reveal that a change in ϕhnp from 0% to 4%, heat transfer is upgraded up to 4.28% in Case I and 3.93% in Case II while mass transfer is declined by 2.24% in Case I and 1.60% in Case II. Results indicate that Case I performed better than Case II in the case of energy and solutal transfer. This work has many practical applications such as heat exchangers, electronic device cooling, food processing and porous industrial processes.

Nonlinear regimes of inertial wave attractors generated by a precessing lid: Zonal flows and Rossby waves

Fluid flow excited by inertial waves in a rotating annulus with a trapezoidal cross section is experimentally investigated. The forcing is introduced by the precession of a flat annular lid bounding the cavity. Such a setup allows to investigate interactions between inertial waves and zonal flows in the presence of equivalent topographic beta-effect, and its dynamic behavior under weak and strong forcing is experimentally studied for the first time. Due to the specific dispersion relation of inertial waves, a cavity shape supports wave attractors that appear only for retrograde lid precession. At a relatively low wave intensity, a zonal flow is generated in the vicinity of a “virtual” axial cylinder, the radius of which coincides with the radius of the focusing reflection from the conical bottom. A succession of non-linear regimes is observed as forcing increases, starting with a clearly identifiable case of triadic resonance. Further, the frequency spectrum is progressively enriched by emergence of additional discrete components, gradually reaching the state of “overheated” wave turbulence with a significant continuous background of the frequency spectrum. Finally, a strong low-frequency component develops in the frequency spectrum, and the continuous background of the spectrum decreases dramatically. The low-frequency component corresponds to azimuthally periodic structures identified as Rossby waves. In the case of strong forcing, a long-term variability of zonal-flow velocity at the timescale of tens of forcing periods is observed, which is likely a consequence of the interaction of azimuthal structures corresponding to a rich wave number set.

Sickles from the Sosnovaya Maza hoard of the Late Bronze Age from the Lower Volga region: Technological analyses, experiments and chronology

The Sosnovaya Maza hoard was discovered by chance in the Saratov region in the Lower Volga in 1901 without any archaeological context. Based on the sickle form and the metal composition–copper with an elevated level of iron–so called Sosnovaya Maza type of sickles was singled out. The comparative analysis of the production technology and the alloying and lead isotope composition of the Sosnovaya Maza type of sickles found in the Volga region, in the Urals and the northern Kazakhstan sites helped obtained more data on the metalworking of this period which became a wide spread activity and required search of new deposits and new sources of surplus.The tracewear study assessed that all sickles were cast in a univalve mold with a flat lid. The ICP-MS analysis determined a rather high heterogeneity of the hoard item elemental composition as well as significant variability in the level of trace elements in the metal. Research experiments through smelting of chalcopyrite raw material and native copper from the Osenneye copper pyrite deposit in Ural melt was conducted, the copper obtained in general correspond to the copper composition of the Sosnovaya Maza tools.Significant variability of the isotope ratios of lead isotopes of Sosnovaya Maza hoard items confirms our hypothesis that raw material came from several ore sources: copper pyrite deposits in the southern Urals (the Trans-Urals and the northern periphery of the Urals-Mugodzhary region); Late Permian oxidized ores of the Urals from the Kargaly (Sakmar-Samara region) mining; and the metallurgical region and deposits characterized by the very radiogenic 208Pb/204Pb, localization of which at the moment does not seem possible. The analyses of the Alekseyevskoye items imply that it might be northern Kazakhstan.The 14C date obtained is used as a chronological marker for the Sosnovaya Maza type sickles and the entire Sosnovaya Maza hoard. This enabled us to narrow down the time interval during which such sickles made from ferrite copper were used and date the hoard to 1400–1300 calBC. The study identified the role of new metalworking provinces located in the eastern part of the Eurasian world.

An Inexpensive In Vitro Blood-Feeding System for Wild Aedes albopictus (Diptera: Culicidae)

An Inexpensive <i>In Vitro</i> Blood-Feeding System for Wild <i>Aedes albopictus</i> (Diptera: Culicidae)

Cavity Tightness Preferences of Overwintering Halyomorpha halys (Hemiptera: Pentatomidae).

Brown marmorated stink bug (Halyomorpha halys) (Stål) is a household nuisance pest that seeks shelter in buildings during the winter months. It has been found in a variety of cavities and spaces between building elements, as well as in the objects stored within buildings. This experiment examined the cavity tightness preferences for these insects as they settled in winter refugia. Adult overwintering H. halys were placed in two types of simulated refugia made from rigid material. Each type had a cavity of constant width, while one had a flat lid and constant tightness, and the other had a sloped lid that became tighter as insects moved inside. Adults were allowed to enter and settle, then their locations were recorded. In sloped lid cavities, H. halys tended to settle where the cavity tightness was between 4.5 and 5.5 mm. In the flat lid cavity boxes, H. halys tended to move all the way back. In both configurations, H. halys had a significant tendency to orient their heads towards the cavity entrance. A field comparison of cavity tightness in refugia with less rigid cardboard substrates was also performed, with spacers consisting of one or two layers of 3-mm cardboard. This comparison found differences in cavity selection by sex, with males more likely to pick single-spaced layers, and females more likely to select double-spaced layers. Understanding these preferences could be useful for collection, pest management, trap design, and study of impacts on structures.

Roman cenotaph from Napoca

The article focuses on an interesting discovery in the immediate vicinity of the Roman city of Napoca, next to the Roman road connecting the city to the settlements located eastward, and in the context of a funerary area. The fragmentary skeleton of a lamb of 1.5 – 2 months was discovered within a sarcophagus with flat lid and without any decoration. It seems that we deal here with an interesting type of cenotaph. The funeral inventory was poor, consisting of two lead objects. A ceramic bowl was also deposited near the sarcophagus.

Improved capture of Drosophila suzukii by a trap baited with two attractants in the same device.

The improvement of trap-lure combinations is an important part of integrated pest management programs that involve monitoring pests for timely insecticide applications, or for their use in control strategies such as mass trapping or bait stations. In this study improvements in the capture of Drosophila suzukii were not observed following the inclusion of different color stimuli with respect to a red-black stripe cup trap. This red-black stripe trap with a hemispherical dome-shaped lid had a significantly improved physical retention of flies compared to traps fitted with a flat lid. Retention was further improved when an additional tube device, which could be baited with a supplemental attractant, was introduced through the dome-shaped lid. Under laboratory conditions, this trap, in which apple cider vinegar + 10% ethanol was present as the drowning solution and the additional tube device was baited with a fermenting mixture of sugar and yeast, was significantly more effective in catching D. suzukii flies than other conventional attractants or a commercial lure. The capture rate of this trap-lure combination remained higher than that of a commercial lure, even after 20 days of use under laboratory conditions. In a guava orchard this trap was 15-fold more effective in catching D. suzukii flies than similar traps baited with apple cider vinegar alone, 4 to 7 fold more effective than similar traps baited with a commercial lure, and 1.7-fold more effective than a fermenting mixture of yeasts and wheat flour. In commercial blackberry orchards, this trap was 6-fold more effective in trapping D. suzukii flies than the clear trap baited with apple cider vinegar used by growers. The efficacy of this trap presents a promising line of future research for monitoring and control of D. suzukii and likely other drosophilid pests.

Onset of three-dimensional flow instabilities in lid-driven circular cavities

Three-dimensional instabilities for two circular lid-driven cavities are investigated by a linear stability analysis and direct numerical simulations using high order spectral techniques. Two circular geometries have been analysed and compared: a circular cavity with a horizontal top boundary and a circular cavity with a circular lid. Compared to more classic results for squared and rectangular lid driven cavities, the corners of these rounded geometries have been partially or totally removed. Critical Reynolds numbers, neutral curves, and three dimensional structures associated with the least stable modes have been identified by the linear stability analysis and then confirmed by spectral direct numerical simulations. We show that the geometries that present fewer sharp corners have enhanced stability: the circular cavity with a flat lid presents the first bifurcation at (Rec,kc)≈(1362,25) whilst the circular lid bifurcates at (Rec,kc)≈(1438,18), where Rec is the critical Reynolds number based on the cavity diameter and lid tangential velocity, and kc is the spanwise wavenumber. Neutral curves and properties of the leading three-dimensional flow structures are documented, and analogies to instabilities in other lid-driven cavities are discussed. Additionally, we include results for the adjoint problem and the structural sensitivity 3D iso-maps (i.e., wavemaker regions), to show that the cavity corners play a relevant role in the generation of 3D instabilities.

A molecular and morphological reassessment of Diademaceae.

We revisit the family Diademaceae based on available sequence data and morphology. Diademaceae is characterized by ascomata opening with a flat circular lid and fissitunicate, short orbicular frequently cylindrical, pedicellate asci. Ascospores are frequently circular in section but narrowing to one end with three or more transverse septa, without longitudinal septa, and mostly with a thick sheath. In recent treatments Clathrospora, Comoclathris, Diadema, Diademosa, and Graphyllium were placed in the family. Following molecular and morphological study, Clathrospora, Comoclathris, and Diademosa, are excluded from the family and referred to Pleosporaceae. Graphyllium is excluded from Diademaceae, based on hysterothecium-like ascomata with a longitudinal opening, and tentatively placed in Hysteriaceae with uncertainty; species with hysterothecia have now been accommodated in at least five families. The study accepts only Diadema in the family. The status of Diademaceae as a distinct family, based on the ascomata opening by a flat circular lid, is thought to be doubtful. Fresh collections of Diadema are needed for epitypification and to obtain sequence data to establish if this is a well-resolved family.

Towards a Monograph ofDothideomycetes: Studies onDiademaceae

Abstract The family Diademaceae presently comprises the genera Clathrospora, Comoclathris, Diadema, Diademosa and Graphyllium and is characterized by ascomata opening as a flat circular lid, bitunicate asci and ascospores with three or more transverse septa, with or without longitudinal septa. The ascospores are fusiform, brown, mostly applanate and usually have a mucilaginous sheath. The type species of Clathrospora, Comoclathris and Graphyllium are revisited in this paper and re-described and illustrated with light micrographs based on examination of holotype specimens. The status of the family is discussed based on morphology and sequence data. Comoclathris is excluded from the family based on morphology and phylogenetic analysis, and should be accommodated in Pleosporaceae. Clathrospora is tentatively placed in Pleosporaceae pending molecular studies. Graphyllium has hysterothecial ascomata with a slit-like ostiole and should be excluded from Diademaceae. It can be accommodated in Hysteriaceae, but wi...

A Cost-Effective MEMS Cavity Packaging Technology for Mass Production

Cost effective microelectromechanical system (MEMS) packaging methods have been required, because the cost portion of the MEMS package is more than 80% of the manufacturing cost of a MEMS device. For this reason, cost-effective MEMS packaging is proposed in this paper for mass production using copper (Cu) lead frames (L/F) as a preplated frame (PPF). Package types include an epoxy molding compound (EMC) cavity wall and an on-frame type. The EMC-cavity package consists of a substrate, a cavity wall and a flat lid on top of the cavity. The on-frame package has a folded lid without a cavity wall. Finite element method (FEM) numerical modeling is performed to anticipate the mechanical warpage and stress of the packages. Assembled MEMS cavity packages were tested for wire pulling, lid pulling, hermetic test, and reliability tests in order to prove the feasibility of this packaging. The wire bonding strength was improved by 40% using plasma cleaning before wire bonding. Through a lid pulling test, a lid bonding strength of 2.40 kgf on average was obtained using an epoxy adhesive. Finally, all samples of the packages passed the reliability tests of the TC, HAST, and HTST, standardized by Joint Electron Device Engineering Council (JEDEC). Also, this cavity package showed excellent hermeticity through leak tests.

A numerical study of the influence of bump type triggers on the axial crushing of top hat thin-walled sections

This paper deals with the issue of a trigger design and its performance. In this respect, a numerical investigation is carried out to study the effects of the geometrical features of a bump type trigger on the crush behavior of an energy absorbing member subjected to axial impact loading. The member was constructed by joining a top hat profile with a flat lid. The trigger was considered to be a bump with a semi-circular cross section on the hat profile. The finite element solver, LS-DYNA was used in all crush simulations. As a result, the introduction of the trigger was found to be effective on the peak crush force and the energy absorption capability of the member under axial impact loading. It was also shown that the crush response could be controlled by varying the location and the geometry of the trigger.

Interface thermal characteristics of flip chip packages – A numerical study

Flip chip ball grid array (FC-BGA) packages are commonly used for high inputs/outputs (I/O) ICs; they have been proven to provide good solutions for a variety of applications to maximize thermal and electrical performance. A fundamental limitation to such devices is the thermal resistance at the top of the package, which is characterized θ JC parameter. The die-to-lid interface thermal resistance is identified as a critical issue for the thermal management of electronic packages. This paper focuses on the effect of the interface material property changes on the interface thermal resistance. The effect of package’s junction to case (Theta-JC or θ JC) thermal performance is investigated for bare die, flat lid and cup lid packages using a validated thermal model. Thermal performance of a cup or flat lid attached and bare die packages were investigated for different interface materials. Improved Theta-JC performance was observed for the large die as compared to the smaller die. Several parametric studies were carried out to understand the effects of interface bond line thickness (BLT), different die sizes, the average void size during assembly and thermal conductivity of interface materials on package thermal resistance.

Exposed Die-Top Encapsulation Molding for an Improved High- Performance Flip Chip BGA Package

The recent advancement in high- performance semiconductor packages has been driven by the need for higher pin count and superior heat dissipation. A one-piece cavity lid flip chip ball grid array (BGA) package with high pin count and targeted reliability has emerged as a popular choice. The flip chip technology can accommodate an I/O count of more than five hundreds500, and the die junction temperature can be reduced to a minimum level by a metal heat spreader attachment. None the less, greater expectations on these high-performance packages arose such as better substrate real estate utilization for multiple chips, ease in handling for thinner core substrates, and improved board- level solder joint reliability. A new design of the flip chip BGA package has been looked into for meeting such requirements. By encapsulating the flip chip with molding compound leaving the die top exposed, a planar top surface can be formed. A, and a flat lid can then be mounted on the planar mold/die top surface. In this manner the direct interaction of the metal lid with the substrate can be removed. The new package is thus less rigid under thermal loading and solder joint reliability enhancement is expected. This paper discusses the process development of the new package and its advantages for improved solder joint fatigue life, and being a multichip package and thin core substrate options. Finite-element simulations have been employed for the study of its structural integrity, thermal, and electrical performances. Detailed package and board-level reliability test results will also be reported

Minimal Radius of Curvature of Lipid Bilayers in the Gel Phase State Corresponds to the Dimension of Biomembrane Structures “Caveolae”

Caveolae are membrane invaginations with a radius of curvature in the range of 40 nm for the bulb; 10–15 nm is the minimal radius for lipid bilayers in the liquid-crystalline Lα(liquid-disordered:ld) phase state. A minimal radius of 20–30 nm could be detected for the gel phase state by analysis of convex–concave bilayer deformations. Circular protrusions with a diameter in the range of only about 40 nm are closed by a flat lid, and those with diameters of 60 nm or more are closed by hemispherical caps. These structures are found primarily in phosphatidylcholine/sterol mixtures, where the gel phase state “liquid ordered” (lo) has been introduced. As a further example the mixture of dimyristoylphosphatidylcholine (DMPC) with an unusual sterol (diflucortolon-21-valerat) is presented. In the usual hydration at temperatures above the phase transition the deformation requires an incubation at 4°C for several weeks or months to form. Using a low temperature hydration procedure (at 4°C), surprisingly bilayers of pure DMPC and DPPC (dipalmitoylphosphatidylcholine) are found to deform in the same convex–concave manner, and this takes place within hours and days. The dependence on hydration protocol is also observed for formation of a sponge-like bilayer network with 30–35 nm radius of curvature in brain sphingomyelin and its mixtures with cholesterol. Caveolae are microdomains enriched in cholesterol and sphingomyelin and are simultaneously discussed to be in thelostate. Direct evidence by investigation of bilayers formed by the lipids isolated from caveolae is still lacking, but structures similar to caveolae which are in the gel phase state (very probably thelostate) are also formed by lipids extracted from bacterial membranes. A further analogy exists because both natural lipid mixtures (brain sphingomyelin and bacterial lipids) transform during heating from the curved bilayer structures into microvesicles above the phase transition. Internalization of caveolae is a process of vesicle formation.

Multichannel fiber ferrule for a stable laser-diode array module

We developed a multichannel fiber ferrule for a stable laser-diode array module. To apply YAG laser welding to parallel butt couple between the laser-diode and the single-mode fiber arrays, hermetically sealed and precisely aligned equi-interval fibers are required. We describe a V-grooved ceramic ferrule for embedding fibers. Fibers are fixed by soldering, using a flat ceramic lid and aligned with a 250 μm pitch. Our ferrule allowed a metallic, stem mounting laser-diode, to be fixed by YAG laser welding. All 30 samples tested have a leak rate of less than 1×10/sup -10/ atm/spl middot/cc/s. Optical coupling of fabricated modules was 9.7/spl plusmn/0.2 dB and coupling loss change from 25/spl deg/C to 115/spl deg/C was within 0.5 dB.

Applanodictyosporous Pleosporales: Clathrospora, Comoclathris, GraphyIlium, Macrospora, and Platysporoides

Six genera of the order Pleosporales are revised taxonomically. Although five genera have unusual applanate ascospores, they are members of three different families. Clathrospora (10 species, 2 new), Comoclathris (21 species, 7 new), and Macrospora (3 species) are placed in a new family Diademaceae in which the ascoma opening is a characteristic flat circular lid. Diademosa, a new genus with one species with terete ascospores is placed in Diademaceae. Graphyllium (3 species) is placed in the family Hysteriaceae characterized by hysterothecia with a slit-like opening. Platysporoides n.gen. (11 species, 1 new) is maintained in the Pleosporaceae because of the terete pored beak of the ascomata. Key words: Pleosporales, applanate ascospores, Clathrospora, Comoclathris, Macrospora, Diademosa, Graphyllium, Platysporoides.

A new instrument and technique for diagnosing electromagnetic design problems in microwave module housings and component packages

A method of measuring the frequencies at which resonances occur and the distribution of the associated electric field intensity at the inside face of the housing or package lid has been developed and tested. The method does not require modification of the connections to the microwave assembly within the housing. It is only necessary that the housing or package have a flat lid and that it be left off so that the item under test can be mounted on an equivalent flat plate on the test instrument. The microwave assembly in the housing or package may be operated normally while resonant field distributions are being measured. The prototype instrument yields results that demonstrate the practical application of this measurement assembly as a diagnostic and design development tool for microwave housings and packages of rectangular metal box basic shape. Resonances in the 8-12 GHz range have been accurately measured and indicate that by scaling dimensions an assembly for use at millimeter wavelengths is feasible.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A molded polymeric resin-filled coupler

A novel type of molded polymeric resin-filled coupler has been built with the goal of making a low cost and manufacturable 1*N multimode optical coupler. The coupler consists of a low index thermoplastic molded cladding piece part containing an optically finished waveguide channel. The channel is covered with a flat lid of the same material and is filled with a high index resin to form a mode mixing waveguide. Optical fibers are inserted into both ends of the channel before it is filled to complete the pigtailed device. The design accomplished all required tasks with just two materials: the molded low index structural part which provides the waveguide cladding, and the high index waveguide core part which provides the adhesive to hold the fibers in place and the optial refractive index matching to reduce reflections. Two different material systems have been used to construct 1*23 couplers. Typical coupler excess losses are less than 2 dB, and the uniformity among all fibers is better than a 1 dB standard deviation. >

A note on the mass flux for rapidly rotating recycling flow over topography

This paper reports some measurements of the circumferential mass flux in a rotating cylindrical annulus spanned by a transverse ridge and containing a homogeneous liquid. Flows are driven by a differentially rotating lid in the shape of a parabola so as to simulate a polar ?-plane. Unless the Rossby number R o = ?/2?, based on the lid rotation rate ? and the basic rotation rate ?, is quite small the mass flux is less for the ?-plane than for f -plane (flat lid) geometry. The mass flux is reduced in the ?-plane case by mountain wave drag associated with the formation of Rossby waves in the annulus downstream of the topography. When R o 2 is less than the Ekman number the ?-plane mass flux exceeds that of the f -plane case. Streak photographs demonstrate the qualitative nature of the flow. DOI: 10.1111/j.2153-3490.1981.tb01784.x 2