Two-line Model Research Articles

Flexural cracking behaviour and crack width calculation of steel-plate-reinforced ribbed UHPFRC deck panels

Ribbed ultra-high performance fiber reinforced concrete (UHPFRC) deck panels have been designed and implemented in buildings and bridges due to being increasingly slender, lightweight and tough. To further improve the crack resistance, this paper studies a neotype ribbed UHPFRC deck panel using steel plates and headed studs to reinforce the ribs. Bending tests were conducted to reveal the various crack and strain developments at different specimen parts with an aim to selecting the interesting primary-crack position and spacing. Then, theoretical calculation equations were proposed and verified on the differential strain, crack spacing and crack width for the interesting primary crack. The test results showed that the maximum crack width was invariably located at the rib instead of the top slab, and the primary-crack spacing varied from 52.1 mm to 151.2 mm after the cracks penetrated the whole rib into the top slab. The theoretical study showed that the tensile property of UHPFRC can be taken account by a two-line model, the shrinkage strain of UHPFRC as 556.5 με herein should be amended in the equation of the differential strain between reinforcement and UHPFRC. Besides, the crack spacing before and after the cracks penetrated the whole rib can be predicted by the standard AFNOR: 2016 and the headed-stud spacing, respectively. Finally, the theoretical crack-width calculation method was verified to have a satisfactory accuracy by comparing the calculated and test results with a percentage error within 4.0 %.

A mediator of OsbZIP46 deactivation and degradation negatively regulates seed dormancy in rice

Preharvest sprouting (PHS) is a deleterious phenotype that occurs frequently in rice-growing regions where the temperature and precipitation are high. It negatively affects yield, quality, and downstream grain processing. Seed dormancy is a trait related to PHS. Longer seed dormancy is preferred for rice production as it can prevent PHS. Here, we map QTLs associated with rice seed dormancy and clone Seed Dormancy 3.1 (SDR3.1) underlying one major QTL. SDR3.1 encodes a mediator of OsbZIP46 deactivation and degradation (MODD). We show that SDR3.1 negatively regulates seed dormancy by inhibiting the transcriptional activity of ABIs. In addition, we reveal two critical amino acids of SDR3.1 that are critical for the differences in seed dormancy between the Xian/indica and Geng/japonica cultivars. Further, SDR3.1 has been artificially selected during rice domestication. We propose a two-line model for the process of rice seed dormancy domestication from wild rice to modern cultivars. We believe the candidate gene and germplasm studied in this study would be beneficial for the genetic improvement of rice seed dormancy.

Performance and Stability of Tenofovir Alafenamide Formulations within Subcutaneous Biodegradable Implants for HIV Pre-Exposure Prophylaxis (PrEP).

A critical need exists to develop diverse biomedical strategies for the widespread use of HIV Pre-Exposure Prophylaxis (HIV PrEP). This manuscript describes a subcutaneous reservoir-style implant for long-acting delivery of tenofovir alafenamide (TAF) for HIV PrEP. We detail key parameters of the TAF formulation that affect implant performance, including TAF ionization form, the selection of excipient and the exposure to aqueous conditions. Both in-vitro studies and shelf stability tests demonstrate enhanced performance for TAF freebase (TAFFB) in this long-acting implant platform, as TAFFB maintains higher chemical stability than the TAF hemifumarate salt (TAFHF). We also examined the hydrolytic degradation profiles of various formulations of TAF and identified inflection points for the onset of the accelerated drug hydrolysis within the implant using a two-line model. The compositions of unstable formulations are characterized by liquid chromatography-mass spectrometry (LC-MS) and are correlated to predominant products of the TAF hydrolytic pathways. The hydrolysis rate of TAF is affected by pH and water content in the implant microenvironment. We further demonstrate the ability to substantially delay the degradation of TAF by reducing the rates of drug release and thus lowering the water ingress rate. Using this approach, we achieved sustained release of TAFFB formulations over 240 days and maintained > 93% TAF purity under simulated physiological conditions. The opportunities for optimization of TAF formulations in this biodegradable implant supports further advancement of strategies to address long-acting HIV PrEP.

Compact 41–93 GHz symmetric quadrature hybrid based on multi‐conductor coupled line in 65 nm CMOS process

The development of a compact 41–93 GHz symmetric quadrature hybrid based on multi-conductor coupled lines in standard 65 nm bulk CMOS process is presented. The equivalent two-line model of the multi-conductor coupled line is derived and analysed with even/odd mode theory and ABCD matrix. With the multi-conductor coupled-line sections, high coupling coefficient, compact size, and wideband operation can be realised; meanwhile, keeping the responses of four ports fully symmetric, which is suitable for circuit applications demanding port symmetry. Designed compact symmetric quadrature hybrid is implemented with 65 nm bulk CMOS process. Measured results show the CMOS quadrature hybrid has good phase difference within 90 ± 2.5° and amplitude balance <±0.5 dB from 41 to 93 GHz, or a 75.5% fractional bandwidth, with an extremely compact size of 93 µm × 149 µm (0.0138 mm2), or 0.051λ 0 × 0.024λ 0.

Inverse Estimation of Sand Transport Rates on Nourished Delaware Beaches

The Delaware Atlantic coast of 40 km length is suffering from beach erosion. The State of Delaware placed approximately 1,100,0001 m3 sand on its four beaches in 1998. Beach profiles were surveyed along fixed 65 cross-shore lines almost semiannually for 9–11 times until 2005. The measured profiles are analyzed to obtain the shoreline displacement and the area changes in the landward and shoreward zones between the two successive profile surveys. The relations among these profile change parameters indicate that a standard one-line model may not be applicable to these nourished beaches because of the dominant summer and winter profile changes. An inverse method based on a two-line model is developed to estimate the cross-shore sediment transport rate and the gradient of the longshore sediment transport rate. The estimated rates indicate the importance of both cross-shore and longshore sediment transport to predict the evolution of these nourished beaches with large variabilities in time and space.

Inference and Estimation in a Changepoint Regression Problem

The two-line model when the location of the changepoint is known is introduced, with an F-test to detect a change in the regression coefficient. The situation when the changepoint is unknown is then introduced and an algorithm proposed for parameter estimation. It is demonstrated that when the location of the changepoint is not known the F-test does not conform to its expected parametric distribution. Nonparametric bootstrap methods are proposed as a way of overcoming the problems encountered. Finally, a physiology example is introduced where the regression change represents the change from aerobic to anaerobic energy production.

A morphological behaviour model for the outer delta of mixed-energy tidal inlets

The long-term evolution of the seaward part of mixed-energy tidal inlet systems is analysed and modelled mathematically in terms of aggregated morphological parameters. The model is an adapted version of a two-line model, in which empirical information on the equilibrium state of the outer delta is included. Thus detailed computations of the water and sediment motion at the hydrodynamic time scale are avoided. The viability of the concept is tested and the model is verified against data from one of the inlets of the Western Wadden Sea. The results of a number of practice-based applications are shown and discussed.

Thermally Coupled Reynolds Flows: The Poiseuille Component

Equations from an earilier study of steady plane Couette flow are modified to apply to plane Poiseuille flow with dissipative heating, in a fluid where viscosity drops with rising temperature. Three characteristic fluid models are considered: power-law, exponential, and a two-line approximation. Numerical calculations show that all predict similar fluid behavior when the fluids are made to correspond as to fluidity φ, and dφ/dt at the maximum temperature in the channel or film. The two-line model provides useful exact solutions, expressed in simple equations. Using this, the flow is shown to approach a condition where almost half the film is occupied by nearly rigid material, while viscous sliding is restricted to the remainder of the flow. In the asymptotic high-speed flow, pressure gradient along the flow drops with increased volume flow. Presented at the 35th STLE/ASME Tribology Conference In Fort Lauderdale, Florida October 16–19, 1989

Motional narrowing of the rotational Raman band of compressed CO, N2, and CO2

The depolarized rotational Raman, and depolarized Rayleigh spectra of compressed CO, N2, and CO2 were measured. The spectra, particularly that of CO2, show motional narrowing, collapsing to a single line at the laser frequency. The spectra are interpreted in terms of the J diffusion model and in terms of a simple two-line model spectrum. From the analyses, an empirical method is established for estimating the density at which motional narrowing will occur in rotational Raman bands. Two minor shortcomings in the J diffusion model are also identified.