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71.
通过有限元理论计算及既有桥动力性能测试,指出大准线既有简支T梁横向刚度不能满足线路扩能需要,需要进行加固。从机理上对影响桥跨动力性能的因素进行了分析,指明了加固的总体方向。利用MIDAS/Civil有限元软件,对不同加固方式进行计算,比较并确定了最优加固思路,最终给出了推荐方案:加宽梁两端上下横隔板各0.65 m,且对加宽部位施加横向预应力。理论及实测结果表明,加固方案合理可行。  相似文献   
72.
设计了一种不同于传统智能算法如自适应控制与模糊控制等的智能控制算法,该算法基于目标输入关系网络, 借鉴强化学习的思想,采用输出试探与评价进行学习,是一种模型无关的控制算法,该算法可以与随机优化算法结合,通 过实验,验证了其在控制过程中有效性,并通过与遗传算法结合,验证了与遗传算法相结合的该智能算法的控制效果。  相似文献   
73.
在纤维梳理机中,辊筒是决定设备成败的关键零部件。分析了辊筒在机器中的支承形式、结构特征、运动规律,将正弦变化的轴压、扭转载荷简化为恒定轴压、扭转载荷,得到适合理论分析的辊筒受力模型。利用无矩理论导出了辊筒的挠度和内应力计算公式,分析了辊筒自重、壁厚、轴压、径压、针布层对挠度的影响作用,获得了挠度、强度、稳定性约束条件下的最小壁厚值,指出辊筒加筋没有必要。生产实践结果证明了文中的简化、推演、分析过程及结果安全可靠,对类似辊筒类零部件设计具有参考意义。  相似文献   
74.
How can risk analysts help to improve policy and decision making when the correct probabilistic relation between alternative acts and their probable consequences is unknown? This practical challenge of risk management with model uncertainty arises in problems from preparing for climate change to managing emerging diseases to operating complex and hazardous facilities safely. We review constructive methods for robust and adaptive risk analysis under deep uncertainty. These methods are not yet as familiar to many risk analysts as older statistical and model‐based methods, such as the paradigm of identifying a single “best‐fitting” model and performing sensitivity analyses for its conclusions. They provide genuine breakthroughs for improving predictions and decisions when the correct model is highly uncertain. We demonstrate their potential by summarizing a variety of practical risk management applications.  相似文献   
75.
Individuals with developmental disabilities are often unable to influence their social environment in traditional ways (i.e., vocal language) and frequently exhibit challenging behaviors (e.g., aggression and self-injury) because such behaviors were previously reinforced under similar conditions. While the area of positive reinforcement manding has been well-documented and empirically validated, there is less research in the area of negatively reinforced manding—particularly in the area of negatively reinforced manding of nonpreferred items. Using a multiple baseline design across participants, this study sought to teach three children with autism to replace their challenging behaviors with more socially appropriate ways to request the removal of nonpreferred items. Results showed that all participants were able to learn the negatively reinforced mand response and these mand responses were generalized to other untrained items. In addition to extending the research in the area, the study empirically defined a procedure for teaching negatively reinforced manding of nonpreferred items. Moreover, teaching the mand response resulted in quality of life improvements for all participants and their families.  相似文献   
76.
结合北京地铁十号线工体北路站—呼家楼站区间隧道的具体情况,进行三维动态数值模拟,计算中分别考虑小导管注浆预加固和无预加固措施两种工况,通过数值模拟对比了两种工况下区间隧道台阶法施工过程地表沉降及拱顶沉降规律及小导管注浆预支护对隧道稳定性的影响。  相似文献   
77.
Abstract

Seven thoughtful and provocative commentaries were activated by one or both of two articles I authored or coauthored. One article (Geller, 2002) presented a case for broadening the content of organizational behavior management (OBM), while the other (Wiegand & Geller, 2004) discussed linkages between positive reinforcement, positive psychology, and achievement motivation. This rejoinder explains apparent misperceptions of the earlier papers, and adds to the case for expanding the language and scope of OBM, including a consideration of hypothetical constructs influenced reciprocally by environmental conditions and contingencies. A rationale for success seeking over failure avoiding is given with reference to Skinner's theorizing about freedom and dignity.  相似文献   
78.
The present study examined the effectiveness of a punishment procedure for controlling staff absenteeism in a facility for mentally retarded persons. Subjects were required to report sick leave absences and related information directly to their supervisor. The supervisor then provided subjects with information concerning the effects of the absence on facility operations. Results indicated a reduction in sick leave absenteeism following the implementation of the punishment procedure. Results also showed that vacation leave absenteeism increased systematically with reductions in sick leave absenteeism. Results were discussed in terms of employee-controlled (sick leave) vs. employer-controlled (vacation leave) absenteeism, and the ease and economy of the punishment procedure.  相似文献   
79.
The current study evaluated the effects of a stimulus-stimulus pairing procedure intended to increase spontaneous vocalizations of a young child diagnosed with autism. A multiple-baseline design across two target phonemes was used to evaluate the effects of the pairing procedure on the frequency of phonemes uttered by the participant. Data were collected during presession, postsession, and follow-up periods across three conditions: Baseline, Control, and Pairing. During the Pairing conditions, a target phoneme was repeatedly vocalized by the experimenter and was systematically paired with preferred stimuli. Results from postsession observations following the pairing condition evidenced no increase in the target sounds. Practical and theoretical implications of the results are discussed.  相似文献   
80.
Effects of a stimulus-stimulus pairing procedure on the subsequent acquisition of mand operants were investigated. An attempt was made to shape novel sounds that emerged through the pairing procedure into a mand. Six children, aged two to five years, with moderate to severe language and communication delays, participated. Two conditions were used following the pairing condition: postpairing and direct reinforcement. The emergence of mands was compared across these conditions. An additional analysis was made of the relation between participants'' baseline verbal repertoires and the effects of the pairing and the emergence of mands. Results indicate the possibility of stimulus control from a stimulus-stimulus pairing to mand as shown in two of the participants who had demonstrated high rates of vocal play and low to no verbal repertoire prior to this study. Target vocal sounds during postpairing and direct reinforcement condition remained at zero to low levels for participants with high verbal repertoire and little vocal play, warranting future studies on relations between the pre-existing verbal repertoire and the effectiveness of stimulus-stimulus pairing.  相似文献   
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