Modeling of 1-3 piezoelectric composites operating in thickness-stretch vibration mode

For bulk piezoelectric ceramics plates, the fundamental thickness-stretch (TSt) waves are always coupled to the in-plane extension waves and the symmetric thickness-shear waves. The occurrence of these spurious modes in bulk piezoelectric ceramics plates is undesirable as it may interfere with the operation of transducers. 1–3 piezoelectric composites are promising candidates to suppress the spurious modes mentioned above. However, theoretical modelling of multiphase ceramic composite objects is very complex. In this study, a simple analytical TSt vibration model is constructed from three-dimensional equations of linear piezoelectricity. The mechanical damping is considered in the model by introducing a complex elastic constant. The performance of 1–3 piezoelectric composites is analysed and the electrical impedance results from theoretical and experimental analysis are compared. The results show that there is excellent agreement between the experimental electrical impedance and that obtained by the theoretical TSt vibration analysis. This indicates that 1–3 piezoelectric composites can be operated in a nearly pure TSt vibration mode near the fundamental resonance. The analytical model we present is valid for analysing 1–3 piezoelectric composites plates with large aspect ratios quickly and efficiently.     

Atomic imaging of the interface between M23C6-type carbide and matrix in a long-term ageing polycrystalline Ni-based superalloy

Besides the well-known cube-on-cube orientation relationship (OR) between M₂₃C₆ carbide and matrix, we have determined a new OR named as the twin-related OR in a long-term ageing Ni-based superalloy on the basis of the extensive and detailed electron diffraction analyses. Furthermore, by means of atomic-resolution high angle annular dark-field imaging technique which is implemented in the aberration-corrected scanning transmission electron microscope, we elucidated the interfacial characteristics between M₂₃C₆ and matrix for above two types of ORs. Taking into account of the interfacial characteristics, we propose that the twin-related OR possesses a higher total interfacial energy. Thus, its frequency of occurrence is lower than that of the cube-on-cube OR though both ORs are usually seen in the long-term ageing samples.     

基督教与近代中国

基督教在近代中国的传教事业,依仗不平等条约的庇护,被视为“骑在炮弹上”传播福音。近代中国是基督教教会与民众冲突最为激烈的时期。传教士们推动的文教事业,以文化征服为主要目的,遭到中国社会各阶层的强烈抵制。20年代的非基督教运动高举科学与民主的旗帜,是中国知识阶层的理性批判。在近代中国民族主义思潮的推动下,中国基督教徒走上了“爱教必定爱国”的康庄大道。     

石头希迁“杼载绝岳”考辨

<正>禅宗早期发展史不甚明了,多有疑点。唐代高僧石头希迁(700-790)是禅宗七祖青原行思的唯一嗣法弟子,也是"石头宗"的祖师,对于梳理早期禅宗史具有重要意义。宋代赞宁(919-1002)撰写的《宋高僧传》是研究禅宗早期历史的重要资料,目前《永乐北藏》《乾隆大藏经》《大正藏》等各版本《宋高僧传》中关于石头希迁的传记,内容基本相同,仅少数几处表述略有出入。《希迁传》中"杼载绝岳"四字,各版本虽皆相同,然甚为可疑,之前解释稍显牵强。笔者不揣谫陋,试对此略作辨析。     

The failure to detect tactile change: A tactile analogue of visual change blindness

A large body of empirical research now shows that people are surprisingly poor at detecting significant changes in visually presented scenes. This phenomenon is known aschange blindness in vision. A similar phenomenon occurs in audition, but to date no such effect has been documented in touch. In the present study, we explored the ability of people to detect changes introduced between two consecutively presented vibrotactile patterns presented over the body surface. The patterns consisted of two or three vibrotactile stimuli presented for 200 msec. The position of one of the vibrotactile stimuli composing the display was repeatedly changed (alternating between two different positions) on 50% of the trials, but the same pattern was presented repeatedly on the remaining trials. Three conditions were investigated: No interval between the patterns, an empty interval between the patterns, and a masked interval between the patterns. Change detection was near perfect in the no-interval block. Performance deteriorated somewhat in the empty-interval block, but by far the worst change detection performance occurred in the masked-interval block. These results demonstrate that “change blindness” can also affect tactile perception.     

The rhetorician's craft, distinctions in science, and political morality

In his response to Szasz' Secular Humanism and Scientific Psychiatry, the author considers the use of rhetorical devices in Szasz' work, Szasz' avoidance of acknowledging psychiatry's scientific distinctions, and Szaszian libertarianism versus liberalism.     

Deconstructing therapy outcome measurement with Rasch analysis of a measure of general clinical distress: the Symptom Checklist-90-Revised

Rasch analysis was used to illustrate the usefulness of item-level analyses for evaluating a common therapy outcome measure of general clinical distress, the Symptom Checklist-90-Revised (SCL-90-R; Derogatis, 1994). Using complementary therapy research samples, the instrument's 5-point rating scale was found to exceed clients' ability to make reliable discriminations and could be improved by collapsing it into a 3-point version (combining scale points 1 with 2 and 3 with 4). This revision, in addition to removing 3 misfitting items, increased person separation from 4.90 to 5.07 and item separation from 7.76 to 8.52 (resulting in alphas of .96 and .99, respectively). Some SCL-90-R subscales had low internal consistency reliabilities; SCL-90-R items can be used to define one factor of general clinical distress that is generally stable across both samples, with two small residual factors.