Utility function of TCP

Understanding the TCP congestion control mechanism from a global optimization point of view is not only important in its own right, but also crucial to the design of other transport layer traffic control protocols with provable properties. In this paper, we derive a global utility function and the corresponding optimal control law, known as TCP control law, which maximizes the global utility. The TCP control law captures the essential behaviors of TCP, including slow start, congestion avoidance, and the binary nature of congestion feedback in TCP. We find that the utility function of TCP is linear in the slow start phase and is proportional to the additive increase rate and approaches the well-known logarithm function as the data rate becomes large in the congestion avoidance phase. We also find that understanding the slow start phase with a fixed threshold is critical to the design of new transport layer control protocols to enable quality of service features. Finally, as an application, we design a Minimum Rate Guaranteed (MRG) traffic control law that shares the same utility function as the TCP control law. Our simulation study of the MRG control law indicates that it is indeed TCP friendly and can provide minimum rate guarantee as long as the percentage of network resource consumed by the MRG flows is moderately small.     

Microstructure evolution of the Sn–Ag–y%Cu interconnect

The lead free Sn–Ag–y%Cu (y = 0.0, 0.5, 1.0 and 2.0) interconnect interfacial microstructures and the microstructure evolution under thermal treatment (isothermal aging, 150 °C/1000 h) were studied in detail by using surface microetching microscopy and cross section microscopy. The corresponding mechanical and reliability behaviors were evaluated by performing shear test and fracture mode analysis before and after the thermal treatment. The results indicate: (i) The interconnects could have different microstructures and intermetallic compound (IMC), depending on the Cu content. The Cu–Sn IMC could have microstructures that were clusters or protrusion-like, Augustine grass leaf-like, scissor-like, tweezers-like, etc. (ii) Ag₃Sn IMCs were not observed at time zero for any interconnect groups, but they occurred after the aging for all groups. The Ag₃Sn IMC could have different microstructures, again depending on Cu content. For low Cu content, the Ag₃Sn IMCs were granules or nodules; for higher Cu content, Ag₃Sn IMCs were plate-like. (iii) The growth of Ag₃Sn plates was promoted by the growth of Cu–Sn IMCs, but indirectly linked to the Cu content. (iv) High Cu content (1.0 wt% and higher) could degrade the mechanical and reliability performances of the LF interconnect by providing a brittle joint, which was mainly achieved through the substantial growth of Cu–Sn IMCs and Ag₃Sn plates.     

Sydis and the voice/data terminal craze of 1984

In 1984, computing firms saw integrated voice/data terminals (IVDTs) as the solution to the proliferation of new forms of executive communication. The Sydis VoiceStation was hailed as the best of this new class of office machine but, like all IVDTs, it failed. Sydis succumbed to "integration stress," one danger of product development driven by the urge to integrate traditionally discrete functions. Sydis also failed from poor integration of financial and market actors.     

打造科技应用中心工程化教育模式——专访中科院软件学院院长潘辛平博士

当证监会第二天就找上门来希望合作之前,中科院软件学院院长潘辛平博士并没有预料到他写的“建设金融科技中心”的提案会有这么强的反馈。潘辛平说:“他们希望我们能够在科研、测试、认证和监管方面和我们全面合作,并且提供足够的人才和项目。”事实上,从担任中科院软件学院院长的那一天起,在中国金融科技界享有盛誉的潘辛平就明确了自己的工程化人才教育模式。他认为,工程教育应该比工学教育更加关注流程化、标准化、团队作     

美国火电厂烟气排放限值及控制技术

美国火电厂烟气排放限值及控制技术在过去的37年内不断发展进步.受限制的排放物越来越多,而且对每种污染物的限值日益严格.总结了当今美国使用的排放限值及控制技术,并展望了未来的排放限值及潜在的排放控制技术.     

Comparing true and false confessions among persons with serious mental illness.

Over the past decade, knowledge on false confessions has grown tremendously. However, a similar knowledge base on true confessions has not. In the present study, independent, self-reported true and false confession experiences of persons with serious mental illness were compared. In addition to examining the crimes and police questioning that led to the true or false confession, we investigated the reasons behind the confessions and the eventual case outcomes. We found that, in comparison to true confessors (n = 30), false confessors (n = 35) were questioned more times, took longer to confess, perceived the evidence against them to be weaker, and reported significantly more external pressure and less internal pressure. Moreover, of those participants who were convicted, false confessors were four times more likely to receive a prison sentence than true confessors. (PsycINFO Database Record (c) 2011 APA, all rights reserved)