Giant Piezoelectricity of Ternary Perovskite Ceramics at High Temperatures

Here, novel ferroelectric ceramics of (0.95 ? x)BiScO₃‐xPbTiO₃‐0.05Pb(Sn_1/3Nb_2/3)O₃ (BS‐xPT‐PSN) of complex perovskite structure are reported with compositions near the morphotropic phase boundary (MPB), and which exhibit a piezoelectric coefficient d₃₃ = 555 pC N^?1, a large‐signal coefficient $d_{33}^{?}$ ≈ 1200 pm V^?1 at room temperature, and a high Curie temperature T_C of 408 °C. More interestingly, this ternary system exhibits a giant and stable piezoelectric response at 200 °C with a large‐signal $d_{33}^{?}$ ≈ 2500 pm V^?1, matching that of the costly relaxor‐based piezoelectric single crystals at room temperature. The mechanisms of such giant piezoelectricity and its characteristic temperature dependence are attributed to the spontaneous polarization rotation and extension under an electric field and the MPB‐related phase transition. The findings reveal that the BS‐xPT‐PSN ceramics constitute a new family of high‐performance piezoelectric materials suitable for electromechanical transducers that can be operated at high temperatures (at 200 °C, or higher).     

光合细菌处理啤酒废水的研究

目的:光合细菌(PSB)处理有机污水高效且不带来二次污染。方法:在好氧黑暗条件下光合细菌能有效净化啤酒废水,对啤酒废水进行了处理条件的实验研究。结果:好氧黑暗的处理方式和10~20 m L接种量达到较高的COD去除率。污水COD初始浓度和p H对去除率有影响。结论:光合细菌可以高效降解啤酒废水。     

第三辑：独立建筑师——戴璞：对自己的实践时刻保持警惕

“80后”是我国依法执行计划生育后出生的一代人,多为独生子女,面临的生活、成长、文化发展问题曾受到社会的担忧。他们在变革的社会中成长起来,承担着来自现实和心理上的双重压力。轻狂、张扬、离经叛道、“垮掉的一代”等都曾是大众贴在80后身上的标签。如今,首批80后已迈进30岁门槛,而立之年,首批80后是否已独立起来？     

低时延传输的ERDQN数据调度算法

针对车载网络、远程医疗、工业控制等领域需要低时延、高可靠性的网络传输应用场景,提出了一种经验回放的DQN(experience replay DQN,ERDQN)数据传输调度算法。该算法的主要目的和任务是降低网络时延和提高网络传输的稳定性。ERDQN算法在最后期限感知的传输协议(deadline-aware transport protocol, DTP)的基础上优化了发送端的排队策略,充分考虑了数据块的优先级和截止日期(Deadline),将其作为计算进入等待队列顺序的重要因素,解决了数据块丢失Deadline的问题,降低了网络传输的排队延迟;同时在拥塞控制方面以当前时刻网络传输状态为特征向量,预测下一时刻网络传输状态参数,并赋予不同的奖励因子进行评估,通过ERDQN网络的迭代学习,自动调整到适合当前网络传输的最优参数,在后续的网络链路传输过程中,平均传输速率高且稳定,缓解了网络拥塞和传输不稳定的问题,降低了网络传输时延。实验结果表明ERDQN算法的平均排队时延和传输时延远远低于传统拥塞控制算法(Reno算法),在质量系数(quality of experience, QoE)方面远远高于传统的拥塞控制算法,能够最大程度减少网络传输速率波动、降低丢包率,提供稳定可靠的传输。     

基于VMD-SVD的拉曼分布式光纤测温系统降噪方法

针对分布式光纤测温系统，其产生的包含温度信息的后向拉曼散射信号极其微弱，因此极易被白噪声掩盖的问题。本文设计了一种基于VMD SVD联合降噪算法，并提出通过对构造的仿真信号做降噪对比实验，以更优的降噪性能指标选取该算法的重要参数。实验表明，将该联合算法及EMD、VMD、EMD-SVD算法分别用于多组测试信号降噪时，VMD-SVD降噪算法相较于EMD算法有均有15 dB以上提升，相较于VMD算法有均有9 dB以上的提升，最后相较于EMD-SVD算法也均有1 dB以上提升，最后将上述算法应用于分布式光纤测温系统测量的多组后向拉曼散射信号降噪时，VMD-SVD降噪算法也能最有效的消除该信号的白噪声，为后续高质量测温奠定基础。     

地下柴油发电机室噪声综合治理

为解决某地下柴油发电机引起的噪声污染，设计采用了消声、吸声、隔声的综合治理方案，经测试，综合治理后的环境噪声达到了环保要求     

Effect of the functional groups in ionic liquid molecules on the friction and wear behavior of aluminum alloy in lubricated aluminum-on-steel contact

Four imidazolium-based room temperature ionic liquids containing phosphonyl functional groups, i.e. 1-(3′-O,O-diethylphosphonyl-n-propyl)-3-alkylimidazolium tetrafluoroborates and hexafluorophosphates, were synthesized. The physical properties of the resulting synthetic products were evaluated, and their tribological behaviors as the lubricants for an aluminum-on-steel sliding system were evaluated on an oscillating friction and wear tester, with the emphasis being placed on the effect of the O,O-diethylphosphonyl groups in the ionic liquid molecules on the tribological behaviors. Thus the friction and tests were conducted at a frequency of 25 Hz, a sliding amplitude of 1 mm, and for a duration of 30 min. The worn aluminum surface was analyzed by means of scanning electron microscopy, energy dispersive X-ray analysis, and X-ray photoelectron spectroscopy. It was found that the synthesized ionic liquids had better friction-reducing and anti-wear ability for the aluminum-on-steel system than their nonfunctionalized courterparts (1-ethyl-3-hexylimidazolium tetrafluoroborate, coded as L206, and 1-propyl-3-octylimidazolium hexafluorophosphate, coded as LP308). Especially, they had much better load-carrying capacity than L206 and LP308. The tribological behaviors of the synthetic lubricants were dependent on both the anions and the side-substituted alkyl chains attached to the imidazolium cations. Moreover, physical adsorption and complicated tribochemical reactions were involved during the sliding process of the Al-on-steel system under the lubrication of the synthetic functionalized ionic liquids, which led to the generation of physically adsorbing and chemically reacting films composed of five-member-ring complex compounds, metal fluorides, nitrogen oxide, and FePO₄ on the rubbed Al surface. Those physically adsorbing and chemically reacting films contributed to effectively decrease the friction and wear of the aluminum sliding against steel.     

前驱物和表面活性剂对等离子体电化学法制备银纳米颗粒的影响

利用等离子体电化学法成功制备出银纳米颗粒,并通过局域表面等离子共振效应对颗粒的生长过程进行实时监测,研究了表面活性剂的浓度、种类和前驱物浓度对银纳米颗粒制备的影响。研究结果表明:增大前驱物或表面活性剂浓度对Ag;还原均有促进作用;与聚乙烯吡络烷酮(PVP)和十六烷基三甲基溴化铵(CTAB)相比较,十二烷基硫酸钠(SDS)作为表面活性剂,在相同时间内,生成的银纳米颗粒数量更多,尺寸和形状分布更均匀。     

玉米细胞质雄性不育突变无性系选育

报道了利用生物技术，从具正常细胞质的优良自交系５００３体细胞中，选出细胞质雄性不育（ＣＭＳ）突变无性系（编号：９２－１Ａ）的初步结果。多年对９２－１Ａ分析表明，９２－１Ａ的不育性是稳定遗传的核质互作型，不育性的恢复是受１对显性核基因所控制，不育性可由反Ｂ保持、由Ｅ２８恢复。９２－１Ａ在抗大、小斑病和与Ｅ２８的配合力上，保持或略优于亲本５００３。