Strip Length Research Articles

Flexible thermoelectric Cu–Se nanowire/methyl cellulose composite films prepared via screen printing technology

Cu–Se nanowires (NWs) have been successfully synthesized by a wet chemical method and then flexible Cu–Se NW/methyl cellulose (MC) composite films have been prepared via a screen printing technology. The thermoelectric properties of the composite films were enhanced by a cold-pressing combining annealing treatment. A power factor of 121.87 μWm−1K−2 has been achieved for the Cu–Se NW/MC composite films at 380 K. A flexible thermoelectric generator (f-TEG) assembled by 4-leg of the as-prepared composite films can generate an output voltage of 0.83 mV and a maximum output power of 6.71 nW at a ΔT = 9.5 K. After being bent for 500 cycles, the resistance change ratio of the f-TEG along the strip length direction was only 3.69%, indicating that the f-TEG has a favorable stability. The screen printing process has many advantages, such as low cost, large-scale production, easy for operation, and therefore, it has a great potential for fabrication of flexible inorganic-organic thermoelectric composite films.

Tear film mediators after corneal cross‐linking

AbstractBackground and Purpose: Currently, the gold‐standard treatment of progressive keratoconus (KC) is corneal collagen cross‐linking (CXL), in which riboflavin and ultraviolet‐A radiation increase the corneal biomechanical rigidity, arresting progression. However, post‐operatory results vary significantly among patients. Although it has been suggested that corneal thickness, cone location and patient's age are important factors, their contribution is controversial. The reason for this variability remains obscure. This project aims to find biomarkers that could explain the variability within surgical results after corneal CXL by investigating the correlation between the local corneal inflammatory environment and these results. We hypothesize that better post‐operatory results are related to a reduction in the inflammatory cytokine levels in the patients' tear film. Ultimately, we aim to optimize the patients' surgical outcomes according to their corneal inflammatory environment.Materials and Methods: The research protocol was established after testing different sample collection methods. Patients are interviewed to assess their medical history and relevant habits. Their corneal tomographic and best corrected visual acuity data are registered before and 6 months after surgery. The patient's tear film is sampled twice 6 months apart using Schirmer strips, as the volume yield is larger compared with direct methods (microcapillary tubes or micropipettes), which are more difficult to perform and require stimulation or the instillation of saline into the cul‐de‐sac, originating reflex tearing. The samples are analysed for their total protein content (BCA Protein Assay Kit) and cytokine concentration using Multiplex technology (Th1/Th2/Th9/Th17 Cytokine 18‐Plex Human ProcartaPlex™ Panel) and not ELISA, as we tried before. Statistical analysis to assess sample differences and the correlation between cytokine concentration and tomographic indexes and visual acuity values for each group and subgroup is performed at 6 months.Preliminary results and Discussion: Thirty‐five patients and fifteen control subjects have been enrolled in the study and the first collection of tears has been carried out, as well as some second collections. CXL surgeries for the twenty patients is being performed since October 2020. Two samples were lost due to excessively length of dry Schirmer strip, which we improved by cutting the dry portion. Additionally, the tear fluid from the first eight samples from patients and from control participants was successfully processed for their total protein content.Conclusion: Tear film analysis poses several challenges concerning the small amount of material available without reflex production. This fact precludes the use of conventional ELISA, requiring multiplex modified technology. When dealing with tears it is also important to avoid contamination by using sterilized material, to avoid dilution and to establish an efficient flow of samples from the clinic to the laboratory. This pilot study enabled to identify several methodological frailties and to establish a solid research protocol that can be replicated by other researchers. Understanding the correlation between inflammatory cytokines and surgical outcomes of CXL may allow for the optimization and personalization of CXL. In addition, the results of this research protocol are expected to establish prognostic factors for CXL‐related surgical outcomes, ultimately improving the quality of life of KC patients.

A hybrid solidification enhancement in a latent-heat storage system with nanoparticles, porous foam, and fin-aided foam strips

The relatively high storage density and negligible temperature stratification of phase-changing materials (PCMs) facilitate their application as storage modules for managing the mismatch between energy generation and consumption. The poor heat diffusivity of these materials limits their storage effectiveness, and therefore employing efficient thermal enhancers is required. This study examines the fin-aided foam strip as a hybrid enhancer for overcoming the relatively low thermal response of erythritol as PCM in a triple-pipe containment system. Four different enhancement additives, including porous foam, graphene nanoparticles, longitudinal fins, and foam strips within the same volume limitations, were compared and tested via applying an experimentally validated simulation model to verify the functionality of the proposed thermal enhancers. The results show that the inclusion of full foam, fin arrays, and fin-assisted foam strips substantially enhances the solidifying behaviour of PCM as compared to the inclusion of nanoparticles alone. The solidifying time can be decreased by 60.8 %, 63.2 %, and 77.3 %, while the recovery rate can be increased by 152.9, 171.6 %, and 340.1 %, respectively. The results also suggest that increasing the length of strips while decreasing their thickness can further enhance the thermal response of PCM for solidification within the same volume limitations.

Application of the Deformation Fracture Criterion to Cracking of Disc Specimens with a Central Narrow Slot

Abstract Using the method of singular integral equations, the elastic-plastic problem for cracked Brazilian disk was solved. Based on the Dugdale model and deformation fracture criterion, the relationships between critical load, notch tip opening displacement and length of the plastic strips were established. Also, the comparison between the present solution for the finite domain and the known solution obtained for the semi-infinite notch in the elastic plane was performed.

The Objective Assessment of dry Nose.

Dry nose (DN) is a common symptom in both patients with rhinitis and healthy individuals; however, it is often overlooked. This study aimed to investigate the characteristics of and propose objective diagnostic criteria for DN. This study was conducted from December, 2018 to October, 2021. Patients with complaints of a dry nasal cavity and normal controls were recruited consecutively from the allergy-rhinology outpatient clinic of Beijing TongRen Hospital. Questionnaires were completed by each participant during recruitment to record demographic data. DN test strips were used to evaluate the severity of DN. The length of the strip was recorded at 30 s, 1 min, 2 min, 3 min, 4 min, and 5 min, respectively. Nasal secretions were collected on sponges and allergic status was assessed based on serum sage levels. Twenty (13 men and 7 women) patients with DN and 100 (47 men and 53 women) controls were recruited for the study. The participants' ages ranged from 23 to 73 years (mean = 47.7 years). Nine of the 20 DN patients were diagnosed with vasomotor rhinitis. The weight of the sponges of DN patients was significantly lower than that of controls. At the last time point (5 min), the strips in the control group were significantly longer than those in the DN group. The reference range of 30 s, 1 min, 2 min, 3 min, 4 min, and 5 min of controls was 3.0 mm, 6.0 mm, 10.9 mm, 13.2 mm, 16.8 mm, and 17.0 mm, respectively. Our study indicated that the strip length less than 17.0 mm at 5 min is a valuable reference for the diagnostic of DN in Beijing.

Analysis and fabrication of a small-scale radio-frequency balun for magnetic resonance imaging amplifier.

In this study, the authors report the design and fabrication of a small mixed-integrated balun for magnetic resonance imaging (MRI). The device was designed by using the positive anti-symmetric coupling method, which applies the lump surface-mount technology capacitors as well as mirror-symmetric coupling strips that were etched on the top and bottom layers of a printed circuit board. The capacitors reduced the length of the coupling strips and compensated for imbalances in the phase and gain due to errors in the fabrication process. The structure and equivalent even-odd circuit model of the device was modeled and examined using commercial software to optimize the design parameters. Following this, the device was fabricated and its performance was assessed through measurements using a network analyzer. The results showed that imbalances in the gain and phase were lower than 0.1 dB and 1°, respectively, and the insertion loss and the input voltage standing-wave ratio (VSWR) were lower than 0.4 dB and -25 dB, respectively. More importantly, the device was small, with dimensions of 50 × 60 × 1.5mm. This makes it suitable for MRI applications involving highly integrated miniaturized systems. The proposed device was integrated into a 3.0T radio-frequency power amplifier (RFPA) and reduced the dimensions of its power modules by 20% compared with the traditional balun. Finally, the RFPA module was used in an 3.0T MRI system for imaging experiments, and the results showed that the balun can help obtain high-quality scanning images.

An Improved Approximation for Packing Big Two-Bar Charts

Recently, we presented a new Two-Bar Charts Packing Problem (2-BCPP), in which it is necessary to pack two-bar charts (2-BCs) in a unit-height strip of minimum length. The problem is a generalization of the Bin Packing Problem and 2-D Vector Packing Problem. Earlier, we have proposed several polynomial approximation algorithms. In particular, when each 2-BC has at least one bar of height more than 1/2, we have proposed a 3/2--approximation polynomial algorithm. This paper proposes an $O(n^3)$--time 16/11--approximation algorithm for packing 2-BCs when at least one bar of each BC has a height not less than 1/2 and an $O(n^{2.5})$--time 5/4--approximation algorithm for packing non-increasing or non-decreasing 2-BCs when each 2-BC has at least one bar which height is more than 1/2, where $n$ is the number of 2-BCs.

A novel design scheme for acoustic cloaking of complex shape based on region partitioning and multi-origin coordinate transformation

Acoustic cloaking is an important application of acoustic metamaterials. This article proposes a novel design scheme for acoustic cloaking based on the region partitioning and multi-origin coordinate transformation. The cloaked region is partitioned into multiple narrow strips. For each strip, a local coordinate system is established with the local origin located at the strip center, and a coordinate transformation in the local coordinate system is conducted to squeeze the material along the strip length direction to form the cloaked region. To facilitate the implementation of the acoustic cloak, the multilayer effective medium is used to approximate the non-uniform anisotropic material parameters. The effectiveness of the proposed coordinate transformation method is verified by comparing the results from our method with those in the literature. Firstly, the results of a circular acoustic cloak in the literature are reproduced by using our finite element (FE) simulations for validation. Then, a comparison is made between the traditional coordinate transformation scheme and our new scheme for simulating an elliptical acoustic cloak. The results indicate that the proposed multi-origin coordinate transformation method has a better cloaking effect on the incident wave along the ellipse minor axis direction than the traditional method. This means that for the same object, an appropriate transformation scheme can be selected for different incident wave directions to achieve the optimal control effect. The validated scheme is further used to design an arch-shaped cloak composed of an upper semicircular area and a lower rectangular area, by combining the traditional single-centered coordinate transformation method for the semicircular area and the proposed multi-origin method for the rectangular area. The results show that the designed cloak can effectively control the wave propagation with significantly reduced acoustic pressure level. This work provides a flexible acoustic cloak design method applicable for arbitrary shapes and different wave incident directions, enriching the theory of acoustic cloaking based on coordinate transformation.

Local Wall Cooling Effects on Hypersonic Boundary-Layer Stability

Hypersonic boundary-layer stability has significant importance in vehicle design and successful operation. This paper investigates the stabilization effects of local wall cooling on the hypersonic boundary layers over a 5 deg half-angle blunt cone with a nose radius of 0.0254 mm. We employed a high-order-accurate flow solver to calculate the steady flow for a freestream Mach number of 6.0 and a unit Reynolds number of . In simulations, we considered partial wall cooling, entire wall cooling, and adiabatic wall scenarios. Furthermore, we examined partial cooling parameters such as strip location, length, and temperature profiles. We calculated the growth rates, phase speed, and -factor diagrams using a linear stability analysis. The results showed that complete wall cooling destabilizes the boundary layer. However, the cooling strip upstream of the synchronization point stabilized the boundary layer by damping the disturbances. The longer cooling strip further stabilized the boundary layer. The cooling strip placed downstream of the synchronization point destabilized the boundary layer.

Flexural Strengthening of Reinforced Concrete Beams with Variable Compressive Strength Using Near-Surface Mounted Carbon-Fiber-Reinforced Polymer Strips [NSM-CFRP

An experimental and analytical investigation was conducted on reinforced concrete (RC) beams strengthened in flexure using the near-surface mounted carbon-fiber-reinforced polymers (NSM-CFRPs) technique. A total of 11 full-scale RC rectangular beams were cast and tested under a monotonic three-point bending test, up to failure. The main test variables adopted in this study were the concrete compressive strength (high, medium, and low), the number of CFRP strips, and the strip length. The results indicated that the use of NSM-CFRPs strips in different configurations efficiently increased the load-carrying capacity of the strengthened RC beams, in which all these beams exhibited a higher moment resistance than the corresponding un-strengthened beam. Results also showed that all strengthening schemes were successful in increasing the flexural capacity of the specimens tested. Such increases ranged between 10.36% and 52.28%. Notably, a significant improvement in the ultimate load ratio was observed with beams having a low compressive strength of 17-MPa, then followed by the beams with medium strength (32-MPa), and finally beams with high compressive strength (47-MPa). The NSM technique reduced the occurrence possibility of the CFRP de-bonding failure mode. Furthermore, the test results were compared with theoretical predictions using the ACI 440.2R17 guidelines and showed a good agreement between these results.

Estimating soil water evaporation as influenced by “dry-and green-mulch” cover beneath maize canopy

Soil evaporation reduction can improve rainfed crop production in semi-arid climates. The purpose of this study was to develop empirical models to estimate cumulative soil evaporation (∑Es) from a maize field across the basin and runoff area (BA and RA) of the in-field rainwater harvesting (IRWH) technique as influenced by different levels of stover mulch ("dry-mulch") and canopy shading ("green-mulch"). Soil water evaporation (Es) was measured with micro-lysimeters 300 mm deep and 71 mm in diameter in the BA and RA sections for three consecutive drying cycles. Four different runoff strip lengths, RSL (RSL-1, 1.5, 2 and 3m) and three mulching levels (ML) of bare, 39%, and 96% were used to estimate the Es. The coefficient crop cover (Kcover) values for full and partial canopy shade (FC and PC) on the RA were in the range of 0.46–0.97 and 0.43–0.94, respectively, while in the BA the Kcover values ranged between 0.33 and 0.92. Under IRWH, the ∑Es values from a basin area beneath a maize canopy averaged 42% of the seasonal rainfall. ∑Es proportion of seasonal rainfall is about 62, 64, and 66 percent for bare soil, but as low as 28, 30 and 32 percent for FC, PC, and unshaded canopy (UC), respectively. In conclusion, the microclimate of the cropping system changes according to surface treatments, which greatly affect the Es losses for the IRWH technique and contributes to ET partitioning. Hence, reducing unproductive water losses in dryland crop production improves water use efficiency by storing more water in the root zone for transpiration.

Soil microbial activity as influenced by crusted runoff strip length and mulch cover under in-field rainwater harvesting (IRWH)

A field experiment was designed to provide insight into the system of in-field rainwater harvesting (IRWH) in determining the effect of microbial activities. The treatments that were evaluated include narrow bare (NB) narrow mulch (NM), wide bare (WB) and wide mulch (WM) runoff strips. Soil samples were collected at depths of 5 and 15 cm from the center section of the runoff area and directly from the rhizosphere of the maize roots around basins. From fresh soil samples, Colony Forming Unit (cfu) readings were taken by using a colony counter and total microbial activity was estimated using the fluorescein diacetate (FDA) hydrolysis method. Community-level diversity physiological profiles of the soil samples were assessed by using Biolog EcoPlates™. Results revealed that the mean values of microbial activity indicated the greatest was found under NM rhizosphere (1.611 ± 0.038) and lowest under WB (0.079 ± 0.005) at 5cm depth. Microbial activity under NM at 5 cm was higher (63% increase) than at the rhizosphere (8% increase). However, there was a decrease in the microbial activity of 17% at 15 cm for WM compared to WB. FDA values were positively correlated with measured soil water content across both 5 and 15 cm depths (r = 0.61 and 0.67) and highly significant (r = 90 at P-value ≤ 0.01) for rhizosphere. Some interesting positive correlations between yield and microbial activity were also found however further investigation on microclimatic aspects in association with microbial diversity and activity on soil surface treatments are important for non-uniform canopy structures of IRWH.

Shear retrofitting with manually made NSM FRP sheets (MMFRP) of RC beams

This paper presents an experimental study to evaluate the effectiveness of the proposed carbon manually made fibre-reinforced polymer (MMFRP) folded sheet for shear strengthening of nine RC beams using near-surface mounted (NSM) method, in addition to an unstrengthened control beam. In the laboratory, MMFRP folded sheets were manually manufactured. MMFRP is made by folding an FRP sheet into appropriate groove widths. Carbon MMFRP folded sheets with varying strip amounts, FRP areas and development lengths increase the shear strength of rectangular-reinforced concrete (RC) beams. Double, triple and quadruple strips of FRP were intended to test the enhancement of strength capacity when the strip quantity was just increased without modifying the FRP area and development length. In addition, different FRP areas and development lengths were used to analyse the FRP area and development length of NSM-FRP strips. The advantages of beam strengthening employing different MMFRP folded sheets are explored based on experimental findings. In comparison with the control beam, beams with double, triple and quadruple strips demonstrate 68%, 59% and 74% improvements in shear load-carrying capacity, respectively. However, the study discovered that if the number of strips, FRP area or development length is raised, the member’s shear strength capability is estimated to improve.

32-Channel silicon strip detection module for combined X-ray fluorescence spectroscopy and X-ray diffractometry analysis

A compact detection module for the simultaneous measurement of XRF and XRD in portable analytical applications, in particular in the mining sector, is presented. The detector head is based on 32 silicon strip detectors, fabricated with a low-leakage technology by FBK and readout by two 16-channel low-noise CUBE charge-sensitive amplifiers. The design of the module and its characterization are reported. Multiple configurations are experimentally compared in terms of strip length, spacing, collimation and charge sharing effects. The optimal configuration for a strip length of 6 mm and pitch 0.2 mm is thus identified. It offers an energy resolution of better than 200 eV at 5.9 keV with moderate cooling (−10°C) and peaking time of 14 μs.

Framework of algorithm portfolios for strip packing problem

In this paper selection of fast algorithm portfolios for 2SP packing problem is considered. The 2SP problem consists in placing rectangles on a strip of the given width for minimum strip length. The 2SP packing has application in many industries, but suitability of the related algorithms is limited by their runtimes. While solving combinatorial optimization problems, longer runtimes increase chances of obtaining higher quality solutions. This means that runtime vs solution quality trade-off is important in solving problems such as strip packing. Given some limited runtime, a method is needed to provide the best solution possible. However, a single algorithm outperforming all other methods under all possible conditions usually does not exist. Therefore, algorithm portfolios can reliably provide high quality solutions in the limited runtime. We propose a method choosing algorithm portfolios on the basis of the algorithm performance on a set of training instances. A portfolio covers the instances with the best solutions which could be obtained in the given runtime, subject to the minimum computational cost of the selected algorithms. The portfolios are evaluated in extensive experiments carried out on designed and literature datasets. We demonstrate that our method is capable of carrying over solution quality from the training datasets to the testing datasets. In other words, our algorithm selection method can learn from the training instances. We also compare performance of our portfolio selection method with some other more straightforward approaches to the portfolio selection.

Frequency-Coded and Programmable Synchronous Electromagnetic Encoders Based on Linear Strips

This letter presents electromagnetic encoders where encoding is achieved by considering four different inclusions, particularly linear strips of different length, etched at the predefined positions of the encoder chain, and transversely oriented with regard to the chain axis. Since the length of the strips determines their resonance frequencies, it follows that the 2-bits per inclusion, corresponding to the four possible different states (strip lengths), are frequency-coded. Thus, the reader is a microstrip line with a series gap fed by four harmonic (carrier) signals tuned to the resonance frequencies of the four considered encoder strips. By encoder motion over the reader, each carrier signal is amplitude modulated, with envelope functions exhibiting a peak each time a strip of the encoder chain tuned to the resonance frequency of the considered carrier signal crosses the axis of the reader line. The functionality of the system is experimentally validated in this letter. It is also shown that the encoders can be programmed by considering identical strips and by cutting them appropriately, according to the desired code. The proposed encoders are intrinsically synchronous. Such encoders are useful for measuring displacements and velocities, as well as for the implementation of synchronous near-field chipless radiofrequency identification tags with sequential bit reading.

Ratchetlike motion of helical bilayers induced by boundary constraints.

We show that application of boundary constraints generates unusual folding behaviors in responsive (swellable) helical bilayer strips. Unlike the smooth folding trajectories typical of free helical bilayers, the boundary-constrained bilayers exhibit intermittent folding behaviors characterized by rapid, steplike movements. We experimentally study bilayer strips as they swell and fold, and we propose a simple model to explain the emergence of ratchetlike behavior. Experiments and model predictions are then compared to simulations, which enable calculation of elastic energy during swelling. We investigate the dependence of this steplike behavior as a function of elastic boundary condition strength, strip length, and strip shape; interestingly, "V-shape" strips with the same boundary conditions fold smoothly.

Near-Nature Ecological Technique for Pier Scour Countermeasure in a Submerged Overfall

This paper proposes a near-nature ecological technique, which can consist of a wide range of materials, to protect against pier scouring. The proposed technique can involve the use of many long strips that behave like water weeds. This paper studied a protection method against pier scour by using long strips in a submerged overfall, particularly for a pier located at the maximum depth area of overfall scour. The length and size of the strips were chosen as factors to study their protective effect. Our results showed that this approach slowed the flow velocity between the installed strips and bed. The sediment in flow might accordingly move slowly or even settle down. Thus, the pier could be kept stable and safe by the installation of those strips. Experimental results show that the protective effect is more efficient when the strip length is closer to the pier and has a small diameter. Moreover, the maximum protective effect reached 45.5% scour reduction. Varied lengths provided different protective effects against overfall scour. These findings show that this near-nature ecological technique could be a good and economical solution for pier protection in submerged overfalls.

Kresling origami-inspired reconfigurable antenna with spherical cap

Foldable and reconfigurable helical antennas change shape to adapt and reconfigure their electromagnetic properties. In order to realize the frequency reconfigurability of helical antennas and increase frequency bandwidth, this paper adds a spherical shell to the top of the Kresling origami, so as to achieve maximum frequency reconfiguration and electromagnetic stealth. First, the mechanical properties of the designed antenna during the smart deployment process are analyzed, which can be helically deployed, with super-large compressibility and torsion-contraction coupling effect. Then, the accuracy of the calculation method of Kresling origami-based reconfigurable helical antenna is analyzed, and its geometry is changed to control the performance parameters over time and achieve versatility. Third, the effects of the length of the metal strips and different instability configurations of the spherical shell on the frequency reconfigurability of the antenna in deployable and folded configurations are analyzed. Fourth, multi-port and omnidirectional bending and twisting are used to explore the effect of antenna geometry reconfiguration on electromagnetics. Finally, multiple antennas working at different frequencies but with similar radiation characteristics are concentrated into the same combined antenna aperture through reconstruction, so that the antenna has the capability of multi-frequency operation. Designed antenna has the advantages of compact stowage, easy deployment, light weight, enhanced electromagnetic performance, and multi-functional practicability, which can be widely used in wireless communication systems to provide various services.

Posterior scleral reinforcement for the treatment of myopic traction maculopathy

BackgroundThis study aimed to investigate the clinical effectiveness of posterior scleral reinforcement(PSR) for the treatment of myopic traction maculopathy (MTM).MethodsThis was a prospective study of 32 eyes from 20 patients with MTM treated with PSR using genipin-cross-linked donor sclera. The length of the scleral strip used for the surgery was designed to be 1.5-times the axial length of the eye, whereas its width was 0.4-times the axial length of the eye. The optical coherence tomography images, spherical equivalent of refractive error, axial length, best corrected visual acuity, electroretinogram findings, and intraocular pressure of the patients were assessed postoperatively.ResultsThe mean duration of follow-up was 17.80 ± 8.74 months. The differences between the spherical equivalent of refractive error, best corrected visual acuity, axial length, and electroretinogram findings recorded preoperatively and those measured postoperatively were statistically significant (p < 0.05). The final reduction in axial length was 1.64 ± 0.85 mm. At the end of the follow-up, optical coherence tomography showed essential foveal reattachment in 30 eyes (93.75%), partial reattachment in two eyes (6.25%), and closure of macular holes in seven eyes (77.78%). No retinal detachment, vitreous haemorrhage, or other serious complications occurred following the surgery.ConclusionsPosterior scleral reinforcement with genipin-cross-linked sclera showed safe and effective outcomes for the treatment of MTM during a follow-up period of at least one year.Trial registration11\\12\\2018, ChiCTR1800020012.