强捻纱线织物的服用性能测试分析

采用强捻纱线以平纹组织和斜纹组织进行小样试织,与一般棉织物透气性和耐磨性作对比测试分析。结果表明,强捻纱线织物的透气性和耐磨性都优于普通棉织物;纱线线密度和捻度,织物组织及经纬密度直接影响织物的透气性和耐磨性。     

变扭率扭旋叶片强化传热特性

为探究扭旋叶片的结构参数--扭率变化率Tv对管道换热的影响,以水为介质,在Tv=-5~5范围内,采用实验和数值模拟方法研究了恒壁温条件下流体的传热和阻力特性,并分析了综合传热性能及强化传热机理。结果表明,沿流动方向Tv>0的扭旋叶片安装方式强化传热效果优于Tv=0,研究范围内Tv=2.5时综合强化传热比最高,相对Tv=0平均提高5.0%。而Tv<0时强化传热效果劣于Tv=0,应避免此种叶片安装方式。扭率的变化影响了流场结构,当Tv>0时,在近1/2流动区域内绕流旋涡的涡量和影响区域明显增加,同时,在绕流旋涡流动区域,压力、速度和温度的三场协同程度得到提高,进而强化了换热管道的传热效果。     

冷轧螺纹钢筋材料性能的分析研究与应用

螺纹钢筋分为热轧带肋钢筋和冷轧带肋钢筋。通过实验,从屈服强度、抗拉强度、延伸率、冷弯条件等方面说明了冷轧螺纹钢筋的力学性能标准,并与冷拔螺纹钢筋的力学性能进行比较,得出冷轧螺纹钢筋具有强度较高、塑性良好、锚固性能强及综合力学性能好等优点,为生产用户进一步推广应用冷轧螺纹钢筋提供依据。     

装填有矩形切口螺旋带的管中的湍动传热和压降(英文)

Heat transfer, friction factor and thermal enhancement factor characteristics of a double pipe heat exchanger fitted with square-cut twisted tapes (STT) and plain twisted tapes (PTT) are investigated experimentally using the water as working fluid. The tapes (STT and PTT) have three twist ratios ( , 4.4 and 6.0) and the Reynolds number ranges from 2000 to 12000. The experimental results reveal that heat transfer rate, friction factor and thermal enhancement factor in the tube equipped with STT are significantly higher than those fitted with PTT. The additional disturbance and secondary flow in the vicinity of the tube wall generated by STT are higher compared to that induced by the PTT is referred as the reason for better performance. Over the range considered, the Nusselt number, friction factor and thermal enhancement factor in a tube with STT are respectively, 1.03 to 1.14, 1.05 to 1.25 and 1.02 to 1.06 times of those in tube with PTT. An empirical correlation is also formulated to match with experimental data of Nusselt number and friction factor for STT and PTT.     

One-to-one communication in twisted cubes under restricted connectivity

The dimensions of twisted cubes are only limited to odd integers. In this paper, we first extend the dimensions of twisted cubes to all positive integers. Then, we introduce the concept of the restricted faulty set into twisted cubes. We further prove that under the condition that each node of the n-dimensional twisted cube TQ_n has at least one fault-free neighbor, its restricted connectivity is 2n − 2, which is almost twice as that of TQ_n under the condition of arbitrary faulty nodes, the same as that of the n-dimensional hypercube. Moreover, we provide an O(NlogN) fault-free unicast algorithm and simulations result of the expected length of the fault-free path obtained by our algorithm, where N denotes the node number of TQ_n. Finally, we propose a polynomial algorithm to check whether the faulty node set satisfies the condition that each node of the n-dimensional twisted cube TQ_n has at least one fault-free neighbor.     

XSY型冷拔轧螺纹钢筋拉丝机的开发与研究

给出XSY型冷拔轧螺纹钢筋拉丝机的主要技术参数 ,分析其结构特点及工作原理 ,论述在企业推广使用的发展前景     

Molecular Engineering of Near-Infrared-II Photosensitizers with Steric-Hindrance Effect for Image-Guided Cancer Photodynamic Therapy

The design of photosensitizers (PSs) with fluorescence in the second near-infrared (NIR-II, 1000–1700 nm) window remains a challenge, as the introduction of donor or acceptor units with excessively strong electron-withdrawing or donating ability leads to longer-wavelength emission but insufficient production of singlet oxygen (¹O₂). In this study, a series of acceptor-donor-acceptor-donor-acceptor-type PSs are designed by adjusting the steric hindrance of the molecules. Compound BNET forms a dihedral angle of 88° with a nearly vertically twisted backbone to show that the intensity of local emission in the first near-infrared (750–900 nm) region declines in the aggregated state, while the emission peaks of twisted intramolecular charge transfer span over 1000 nm with significant enhancement. The albumin-bound NIR-II PS nanoparticles exhibit efficient ¹O₂ generation, good photostability and biocompatibility, and negligible dark toxicity. The nanoparticles demonstrate high specific NIR-II fluorescence imaging of tumor lesions as well as effective image-guided photodynamic therapy in mice bearing orthotopic colon cancer or pancreatic cancer. The designed NIR-II PS nanoparticles show great potential for biomedical applications.     

Observation of Electrically Tunable van Hove Singularities in Twisted Bilayer Graphene from NanoARPES

The possibility of triggering correlated phenomena by placing a singularity of the density of states near the Fermi energy remains an intriguing avenue toward engineering the properties of quantum materials. Twisted bilayer graphene is a key material in this regard because the superlattice produced by the rotated graphene layers introduces a van Hove singularity and flat bands near the Fermi energy that cause the emergence of numerous correlated phases, including superconductivity. Direct demonstration of electrostatic control of the superlattice bands over a wide energy range has, so far, been critically missing. This work examines the effect of electrical doping on the electronic band structure of twisted bilayer graphene using a back-gated device architecture for angle-resolved photoemission measurements with a nano-focused light spot. A twist angle of 12.2° is selected such that the superlattice Brillouin zone is sufficiently large to enable identification of van Hove singularities and flat band segments in momentum space. The doping dependence of these features is extracted over an energy range of 0.4 eV, expanding the combinations of twist angle and doping where they can be placed at the Fermi energy and thereby induce new correlated electronic phases in twisted bilayer graphene.     

Dynamic characteristics of a shrouded blade with impact and friction

Frontiers of Mechanical Engineering - A simplified computational model of a twisted shrouded blade with impact and friction is established. In this model, the shrouded blade is simulated by a...