Transverse Partition Research Articles

Reinforcement of Insufficient Transverse Connectivity in Prestressed Concrete Box Girder Bridges Using Concrete-Filled Steel Tube Trusses and Diaphragms: A Comparative Study

To address the issue of insufficient transverse connectivity in prestressed concrete box girder (PCB) bridges, this study investigates two transverse strengthening methods—installing diaphragms and utilizing concrete-filled steel tube trusses (CFSTTs). A finite element model was developed for a typical 30 m PCB bridge and was validated by on-site load test results for reliability. Based on the deflection and load distribution of PCB bridges before and after reinforcement, as well as the maximum stress and strain of the diaphragms and the CFSTTs, comparative analyses were conducted on diaphragms of different thicknesses and materials, as well as on CFSTTs of various strength grades. The results show that the addition of a transverse partition and CFSTTs can effectively improve the load distribution of the PCB bridge and reduce the maximum deflection of the girder, especially when using the CFSTT reinforcement method. The unique structural design improves the reinforcement effect of the material in the post-elastic stage. When using CFSTTs, increasing the steel tube wall strength significantly reduces the maximum deflection of the main girder. For example, using steel tubes with yield strengths of 235 MPa and 420 MPa filled with concrete of 50 MPa compressive strength reduced the maximum deflections by 15.32% and 24.55%, respectively, and improved the load distribution coefficients by up to 7.31% and 11.57%. Additionally, steel diaphragms demonstrated better reinforcement effects compared with concrete diaphragms. The load transverse distribution coefficients for the CFSTT-reinforced PCB bridge were calculated using the hinge plate (beam) and the rigid plate (beam) methods, showing minimal differences between the two approaches. The findings of this study provide valuable insights into the design of diaphragm and CFSTT reinforcement in PCB bridges, aiding in the selection of optimal reinforcement strategies.

Research Progress on Shear Characteristics and Rapid Post-Disaster Construction of Narrow-Width Steel Box–UHPC Composite Beams

The narrow-width steel box girder is an important type of steel–concrete composite bridge structure, which is usually composed of reinforced concrete wing plates, narrow steel boxes partially injected with concrete, and shear connectors that promote shear force transfer. The utilization of narrow-width steel box girders, augmented by partially filled concrete, embodies the synthesis of steel and concrete elements, fostering structural efficiency. Moreover, its attributes, including reduced structural weight, diminished vertical profile, enhanced load-bearing capacity, and augmented stiffness, have prompted its gradual integration into bridge engineering applications. In this study, the calculated values of shear strength under three current design codes were reviewed, and the shear failure phenomena and its determinants of narrow-width steel box–ultra-high-performance concrete (UHPC) composite beams under negative bending moment conditions were investigated, which were mainly determined by shear span ratio, concrete wing plate, UHPC steel fiber content, UHPC plate thickness, and transverse partition inside the box. Concurrently, this paper evaluates two innovative structural designs, including a double-narrow steel box girder and a three-narrow steel box girder. In addition, strategies to reduce crack formation under the negative bending moment of long-span continuous narrow and wide box girder abutments are discussed, and we show that this measure can effectively control the formation of cracks to support the negative bending moment zone. At the same time, the scope of the application of a narrow-width steel box girder composite bridge is reviewed, and the conclusion is that a narrow-width steel box girder is mainly used in small-radius flat-curved bridges or widened-ramp bridges with a span of 30 m or more in interworking areas and in the main line with a 60–100 m span in mountainous or urban areas. Finally, the research direction of the shear resistance of the UHPC–narrow steel box girder under negative bending moments is proposed.

Transport Performance of a Steeply Situated Belt Conveyor

The paper presents a methodology for determining the volume of a batch of conveyed material located before a transverse partition of a certain height and the distance over which the batch of material extends on the working surface of the conveyor belt along its longitudinal axis. Knowing the geometric dimensions of the transported batch of material makes it possible to appropriately set the spacing of the belt cleats and thereby to optimally determine the conveying performance of the inclined belt conveyor. When the angle of inclination of a conveyor with a straight idler frame is equal to the angle of surcharge of the conveyed material, then no layer of material is carried on the surface of the belt. If the conveyor belt is guided along a trough idler frame, only the lower cross-section of the filling of material is used. An increase in the cross-section of the belt load of a conveyor inclined at an angle, which exceeds the angle of repose of the conveyed material, can be achieved by installing regularly spaced belt cleats around the circumference of the working surface of the endless loop of the conveyor belt. The volume of the batch of material retained by the belt cleat depends on the height and width of the cleat and whether or not the conveyor belt is provided with corrugated side edges. The paper presents theoretically determined relationships that can be used to determine the size of the transverse and longitudinal area and the volume of the batch of material spread on the surface of the conveyor belt in front of the cleat. The experiments performed provide the distances of the material distribution on the surface of the conveyor belt depending on the height of the cleat and the angle of inclination of the conveyor belt.

Loose Material Filling in the Loading Trough Profile of the Belt Conveyor

The paper presents a mathematical expression of the sizes of the transverse and longitudinal cross-section surfaces and of the volume of the loose material spread on the surface of the conveyor belt before the transverse partition of the belt conveyor, inclination angle of which exceeds the limit transport angle permitted for the belt conveyor of a classic design. Volume and geometric shape of the lose material; transported in the trough (two-roller bench) loading profile; are impacted by the mechanical characteristics of the transported material, width of the conveyor belt, inclination angle of the side rollers, height of the transverse ribs and especially inclination angle of the conveyor. The maximal cross-section surface of the lose material filling at the conveyor with a smooth belt can be (for conveyor belts modified based on the shape of the trough) expressed as the sum of the cap cross-section surface and the surface of the bottom part of the belt filling. The paper describes the jacket curve of the of the cap cross-section using a parabola equation, and the surface curve of the bottom part of the belt filling using a line equation. The size of the cross-section surface of the belt filling along the longitudinal plane of the conveyor belt is defined as the difference between the inclination angle of the conveyor and the discharge angle of the transported material.

Theoretical study of unloading the body of vehicles equipped with elastic partitions

For transporting potatoes, it is proposed to equip the vehicle with elastic partitions. Elastic partitions are formed by tubes of elastic material and can rotate around the axis of the transverse partition. A model has been developed that allows one to take into account a large number of parameters of root crops, a vehicle body, elastic partitions, parameters of the unloading process, and also calculate the main indicators of the efficiency of unloading root crops. As a result of optimization, it has been found that the optimal length of the elastic tube is 1.58 m (when the height of the vehicle body is 1.60 m), the optimal coefficient of bending stiffness of the tube is 0.9 kN/m2. At the same time, the unloading time will be less than 11.5 s and the share of damaged root crops will be less than 4.0%.

Et monumentalt midtsulehus ved Nørre Holsted i Sydjylland

Et monumentalt midtsulehus ved Nørre Holsted i Sydjylland

Female gametophyte and pollen tube of Epilobium palustre L.

The monosporic, tetranucleate embryo sac of <i>Epilobium palustre (Onagraceae)</i> develops from the micropylar megaspore in a linear tetrad. In mononucleate embryo sacs a peculiar chromatic structure associated with a nucleolus appears in the nucleus. This structure seems to be formed by fibrillar material and is not visible in the subsequant stages of development. A large amount of rough ER cisternae occurs in the late mononucleate stage, during the binucleate stage their contents become optically dense. It the early tetranucleate stage the amount of ER is small, it increases again in the developing synergids and central cell. Numerous amyloplasts present in the mononucleate embryo sac loose their starch grains and some are transformed into cup-shaped plastids or proplastids. They are passed on to each of the embryo sac cells. The growth of the pollen tube ceases immediately after the penetration through the filiform apparatus of a synergid. At the apex of the tube a pore is formed. At the last stages of the penetration the apical part of the pollen tube becomes separated by a transverse partition from the distal part of the tube. The contents of the both parts differ in their internal structure. The distal part contains cytoplasm with numerous organoids, while the apical part is mainly filled with spherical bodies.

Research on Strength Calculation Model of 7A05 Aluminum Alloy Welding Heat-Affected Zone

In order to research the mechanic performance of 7A05 aluminum alloy, a series of tests, including tensile test about aluminum alloy substrate, tensile test about aluminum alloy butt welded joint, tensile test about transverse partition of aluminum alloy welded joint and hardness test were conducted. The results of these tests indicate that the strength and hardness of HAZ of this material exhibit a W-shaped reduction. There are an symmetrical softened area at 10~20mm from the center of weld. Due to ageing effect, the strength and hardness of HAZ can resume to 80%of the substrate one month after welding. Based on the analytical deduction and experimental data fitting, the theoretical strength model for HAZ of aluminum alloy is proposed. For the purpose of engineering design, the HAZ is transformed into a uniform strength reduction zone, the width and strength value is determined according to the principle of equal strength.

Effect of the metal structure on the loss of stability of a thin plate separating a powder compressed by a shock wave

Results of an experimental and theoretical study of the problem of shock-wave compaction of a metallic powder enclosed into a metallic container with a transverse partition are presented. It is demonstrated that internal stresses in the partition generate disturbances, which evolve under explosive loading and compression of the partition together with the powder. In addition to the loss of stability in the powder, which occurs owing to filling of voids, wave formation on the partition is observed.

Transverse structure of wind‐driven flow at the entrance to an estuary: Nansemond River

Observations of current velocity profiles were combined with an analytical solution to study the transverse partition of the wind‐driven flow in an estuary, the Nansemond River, which is a tributary of the James River in the Chesapeake Bay. Observations spanned two periods of nearly 3 months in autumn‐winter of 2003–2004 and spring‐summer 2004. The wind‐driven circulation consisted of downwind flow over the shoal and upwind flow in the channel at the entrance to the estuary. This pattern developed mainly with landward winds and provided observational evidence that sustains analytical and numerical model results. The transverse structure of the flow showed synoptic temporal variability (3–7 days), which corresponded to the variability of winds and sea level. Synoptic variability seemed to be more influential in autumn‐winter than in spring‐summer. However, variability of 1–2 days was persistent in both periods of observation. Also, the transverse structure of the wind‐driven flows was linked to a counterclockwise recirculation pattern previously observed with survey data. Part of the flow going into the tributary over the shoal might recirculate and form or enhance the outflow in the channel. As suggested by the temporal scale of the wind, the recirculation might weaken or even reverse direction every 3–7 days at the entrance to the estuary. Further detailed studies are needed to better define the extent of this recirculation.

Effect of Wave Formation during Shock-Wave Compaction of Powders

The problem of shock-wave compaction of a metal powder enclosed in a metal container with a transverse partition is solved. A model of wave formation on the partition and in the compact adjacent to the partition is proposed; the model is based on the loss of strength in the powder due to collapsing of pores and to development of instability of the partition being compressed in the shock wave.

Mineralization and vascular invasion during endochondral bone formation

The epiphyseal cartilage is composed of the distinct zones of resting, proliferative and hypertrophic chondrocytes. The intercolumnar cartilage matrix of the hypertrophic zone is subjected to mineralization whereas the transverse partitions of the cartilage column are poorly mineralized. Therefore, mineralized cartilage matrices are formed parallel to the longitudinal axis of the epiphyseal cartilage. Vascular endothelial cells invade the cartilage by penetrating the poorly mineralized transverse partition at the chondro-osseous junction, resulting in the exposure of mineralized intercolumnar matrix to bony tissue. The exposed mineralized cartilage matrices appear to serve as scaffolds for osteoblastic attachment. These osteoblasts deposit bone matrices onto the cartilage cores, forming primary trabecular bones. Vascular endothelial growth factor, VEGF, is a strong angiogenic factor, and play a pivotal role in vascular invasion into cartilage. The invading endothelial cells possess the receptor for VEGF, and secret matrix metallo protatenase to digest the cartilage matrices of the unmineralized transverse partition of the column.

The biological role of blood vessels during endochondral bone formation

Endothelial cells play an important role in endochondral bone formation. In the chondro-osseous junction, endothelial cells appear to invade into cartilage by the cellular mechanism of angiogenesis evidenced by cell duplication, disappearance of basement membranes and activated migration. The endothelial cells penetrate the unmineralized transverse partition of the cartilage columns.

Developayella elegans nov. gen., nov. spec., a new type of heterotrophic flagellate from marine plankton

Summary The ultrastructure and possible phylogenetic relationships of a new heterotrophic flagellate are discussed. Two flagella insert into a conspicuous depression which occupies much of the anterior half of the cell. Both flagella contribute to the creation of feeding currents. Their motion is characteristic and reminiscent of a ballet step, the developpe, after which the organism is named. Aspects of the cell ultrastructure such as tubular flagellar masti-gonemes and a transverse partition and transitional helix in the flagella suggest that Developayella is related to the heterokonts (or stramenopiles). However, certain novel features, such as the possession of cortical vesicles and the appearance of part of the posterior flagellar root mean that it is not closely related to any existing group within this assemblage.

Fine Structure of the Fat Body and its Bacteroids in Blattella germanica (Blattodea)

AbstractThe abdominal fat body of the cockroach Blattella germanica contains three characteristic cell types—trophocytes, bacteriocytes and urate cells—which have been investigated by electron microscopy. The trophocytes are rich in lipid droplets of different sizes; glycogen, rough endoplasmic reticulum and mitochondria are also abundant. In females immediately after eclosion, the trophocytes contain a greater number of lipid droplets, some of which have different electron density; glycogen and cytoplasmic organelles are clearly reduced. The bacteriocytes hold rod‐like and spherical bacteroids, which are encapsulated by a vacuolar membrane; they show a thin cytoplasmic membrane and an evident cell wall surrounded by a membrane‐like outer envelope. The bacteroids appear to be dividing either by transverse partition or by budding. The urate cells, adjacent to the bacteriocytes, are characterized by complex urate vacuoles delimited by a double layer‐structure.

New observations on the fine structure of graptoblasts

Graptoblasts are redefined as widenings of the sealed terminal portions of graptolite stolothecae resulting in ovoid bodies composed of an outer fusellar layer, named here as blastotheca, and an inner secondary layer of electron dense material, named the blastocrypt. In their proximal portion a number of graptoblasts display a scar with fuselli stripped and the crassal material of the blastotheca exposed and displaying a rough and dull surface. The boundary of this area, termed the talus, is edged by a distinct escarpment, probably the margin of the preserved part of the blastotheca. The outer wall of the talus is usually abruptly terminated. Only exceptionally is the outer wall conical and gradually widening. Thus the transverse partition between the parental stolotheca and the graptoblast was produced by the blastocrypt without fusellar covering. It seems, therefore, that graptoblasts were most probably lacking any internal portion of their blastothecae which could possibly be compared with the internal parts of a dendroid auto-theca. It is concluded that graptoblasts housed a zooid that never functioned as an autozooid, but suffered arrested development and encystation. The biological role of graptoblasts as dormant bodies is discussed.

Temperature-induced vertical shift of proteins in membranes

Thermotropic changes in the transverse order of microsomal membranes isolated from Tetrahymena are revealed by low-angle X-ray diffraction. These are correlated with the lateral order of the membrane lipids by wide-angle X-ray diffraction. Upon lowering the temperature from 28 °C to 2 °C, the Bragg period of the membrane stack reveals an abrupt increase of ~3.0 nm at ~19 °C, which is reversible upon reheating to 28 °C. This is coupled with an alteration in the electron density profile, revealing a shift of mass from the hydrophobic core towards one of the two hydrophilic surfaces. Between 35 °C and 0 °C, the membrane lipids undergo a broad, thermotropic “two-stage” liquid crystalline ⇋ crystalline phase separation with a “breakpoint” at ~18 °C. This breakpoint signals an abrupt lipid redistribution, presumably due to a change in the composition of the two coexisting liquid crystalline and crystalline lipid phases. We conclude: (1) the temperature-induced mass shift reflects a shift in the transverse partition of proteins in membranes; (2) this is triggered by an abrupt lipid redistribution occurring during a broad liquid crystalline ⇋ crystalline phase separation.

Formation of multinuclear cells induced by dimethyl sulfoxide: inhibition of cytokinesis and occurrence of novel nuclear division in Dictyostelium cells.

Our previous studies showed that 10 percent dimethyl sulfoxide (DMSO) induces the formation of actin microfilament bundles in the cell nucleus together with the dislocation of cortical microfilaments from the plasma membrane. The present study investigated the effects of DMSO on diverse activities mediated by cellular microfilaments as the second step toward assessing potential differences between nuclear and cytoplasmic actins of dictyostelium mucoroides. DMSO was found to reversibly inhibit cell-to- glass as well as cell-to-cell adhesion, cell locomotion, and cell multiplication, whereas cytoplasmic streaming and phagocytosis were not obviously inhibited. Also, 5 percent DMSO inhibited cytokinesis but did not totally inhibit cell growth thus leading to the development of giant cells more than 10 times larger than normal cells. Transmission electron microscopy using serial thin sections showed the occurrence of multinucleation in the DMSO- induced giant cells. After the removal of DMSO, the giant multinuclear cells underwent multiple cytoplasmic cleavage producing normal-sized mononuclear cells. The nuclear division in the DMSO-induced giant cells was unique in that no spindle microtubules were formed, and vesicles appeared inside the nucleus forming a transverse partition of the nuclear envelope. The presence of actin filaments in those nuclei was demonstrated by a binding study with skeletal muscle myosin subfragment-1, and their possible involvement in this mode of nuclear division is discussed.

The repair of larval cells and other larval activities in Geotrupes spiniger Marsham and other species (Coleoptera, Scarabaeidae)

Abstract. 1. G. spiniger larvae repaired openings in their cells by excavating dung from the brood‐mass and placing it in the edge of the hole. Thrusting with the head sealed small holes but pushed dung away from larger defects. Sliding and somersaulting movements allowed repair of different parts of a defect. Repair was provoked by contact with the defect, not by changes in humidity.2. Dung excavated at the anterior end of the cell was transferred by somersaulting, and thrust into the posterior end to seal off foreign bodies. Burrowing by the larvae depended on similar behaviour which moved the whole cell within the brood‐mass.3. Larvae were sensitive to surface contact, making a coordinated attack on a source of stimulation. They also moved towards dung and wet soil.4. Fluid regurgitated by disturbed larvae killed blowfly larvae when injected, and repelled earthworms.5. To construct a pupal cell, excavated material was transferred by somersaulting and used to build a transverse partition without the usual vigorous thrusting movements. The ability to re‐initiate pupal cell formation was retained for about 4 days.6. Larvae enclosed in artificial brood‐balls enlarged defects while attempting to repair them, but larvae just prior to pupation taken from recently made pupal cells could repair such defects.7. Aphodius fossor larvae rarely attempted to repair openings in their cells and usually escaped by burrowing (as above), but opening a recent pupal cell always provoked repair.8. Repair by G. spiniger larvae is closely related to other larval activities but lacks several features that are important for repair by species developing in freestanding brood‐balls.

The occurrence of septate fibres in some New Zealand woods

Abstract Septate fibres were observed in the woods of 66 New Zealand species from 27 genera belonging to 22 dicotyledonous families. They were not observed in 73 species from 41 other genera. When present in one species, they were also recorded for all the other species examined of the same genus but not always for other genera of the same family. The septa were structurally similar, each septum forming a fine transverse partition across the fibre lumen and spreading out at its edges over the inner surface of the normal secondary wall of the fibre. Fine webs of wall material were often observed traversing the inner openings of the pit apertures in the septate fibres.