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© This open access article is distributed under Creative Commons Attribution-NonCommercialNoDerivatives License 4.0 (CC BY-NC-ND). How predictable are life trajectories? We investigated this question with a scientific mass collaboration using the common task method; 160 teams built predictive models for six life outcomes using data from the Fragile Families and Child Wellbeing Study, a high-quality birth cohort study. Despite using a rich dataset and applying machine-learning methods optimized for prediction, the best predictions were not very accurate and were only slightly better than those from a simple benchmark model. Within each outcome, prediction error was strongly associated with the family being predicted and weakly associated with the technique used to generate the prediction. Overall, these results suggest practical limits to the predictability of life outcomes in some settings and illustrate the value of mass collaborations in the social sciences.

In order to ensure the safe operation and timely maintenance on mine flameproof dry-type transformer, we use MATLAB as the platform to get the simulation and to complete the edition of prediction program. After the comprehensively considering the accuracy and timeliness of the algorithm, our final optimization plan is: the GM(1,1) model must be optimized in one aspect: the accumulated order optimization, and then corrected the residuals. Compared to the traditional GM（1,1）model, the optimized and corrected GM(r,1) can improve the accuracy of the prediction result and guarantee the quick reaction of the pre-warning system before the occur of failures. Using this model enables the system to predict the potential faults in a certain period of time in the future, which can improve the actual operation efficiency of mine flameproof dry-type transformer and prolong the transformer’s working life.

In electromagnetic sounding, the detection areas of time-domain and frequency-domain electromagnetic detection methods cannot be effectively connected, and the detection processes for these two methods must be implemented separately. To combine time-domain and frequency-domain electromagnetic detection methods and simplify the detection process, a time-frequency fusion transmission method is proposed to simultaneously excite the earth to produce transient and steady-state responses. By analyzing the characteristics of the time-domain and frequency-domain excitation current waveforms, a pseudorandom transmission waveform with dead time is designed, and a transmission system for a time-frequency fusion electromagnetic detection method is developed. In this detection mode, the pseudorandom transmission waveform contains several frequencies, and the transient induction field can be received during the dead time. The time-domain and frequency-domain responses can be obtained by the same procedure. At the same time, a self-adaptive pseudoload device is designed and matched with the corresponding control sequence to reduce the influence of dead-time. The experimental results show that the self-adaptive pseudoload transmitter can effectively reduce the current fluctuation, and the time-frequency electromagnetic transmission system can effectively excite the earth to produce transient and steady-state responses. The time-frequency fusion electromagnetic transmission method proposed in this paper can be used in electromagnetic detection instruments to improve the efficiency of electromagnetic sounding.

In the process of cold creep forming, the temperature control has problems such as low accuracy and slow response speed. Moreover, the conventional PID temperature controller has poor anti-interference ability and low control accuracy.This paper designs a PID control strategy based on improved ant colony algorithm which is applied to the temperature control of cold creep forming. With the help of Matlab simulation software, a temperature controller simulation model is established, and certain improvements are made to the model on the basis of the traditional ant colony algorithm, applying to search for the optimal parameter combination in PID control. The simulation results show that the designed control strategy can find a better parameter combination than the PID control of the ant colony algorithm. Therefore, the application of this control method to the cold creep forming temperature control system can effectively improve the product quality and production efficiency of the cold creep forming process.

Nowadays, many solutions have been provided to reduce the bandwidth usage of living streaming in the wired part of the Internet, like CDN, P2P, etc. However, it is often overlooked that the capacity of wireless network is inherently limited due to the restriction of wireless spectrum resources. Wireless multicast is a native way to reduce wireless bandwidth usage for living streaming, but it is difficult to deploy due to several problems, like low link data rate, absence of retransmission and lackof multicast support on the Internet. This paper proposes Wi-Live an adaptive wireless multicast solution based on SDN. With the global perspective of SDN, Wi-Live detects potential wireless multicast scenarios where multiple users who associate with the same AP are watching the same live video simultaneously. Then multicast service is adaptively initialized according to the scenarios by Wi-Live. Users watching the same live video are assigned to the same multicast group. A unicast-to-multicast conversion is deployed to generate multicast live video streams. To overcome the shortcoming of traditional wire less multicast, Wi-Live accomplishes a rate adaption scheme to support high rate wireless multicast and adopts FEC for recovery of lost packets. Then we conduct a measurement study based on the real data collected from the campus IPTV platform and the campus wireless network of Tsinghua University. The results indicate that potential wireless multicast scenarios account for a considerable proportion during live video traffic bursts and that high rate multicast is feasible in the campus wireless network. Next, a theoretical analysis on the performance improvement and the overhead of the proposed mechanism is carried out based on the real data as well.

The current wireless communication network is a content-careless network, in which every request needs a new transmission, even those requests imply the same content. However, the Long-Tail distribution of users' interests caused by the converging behavior, determines that the redundant traffic, which is the re-transmission bearing same content, is rather enormous. Therefore the content-careless scheme of network transmission introduces large energy waste. In our previous work, we put forward a novel transmission scheme CASoRT to mitigate such energy waste by broadcasting those hot contents. After the contents are broadcast, the terminals in coverage could cache those contents in local memory and load those contents when request. Thus, the massive redundant transmission of the very content is relieved by one broadcast transmission. In order to exploit the advantage of broadcast, the proper recommender scheme, deciding which contents should be broadcast, needs to be optimized. In this paper, we present certain perspective in analyzing the log of campus network in Tsinghua University. It shows that utilizing users converging character could improve the efficiency of CASoRT with analysis. Finally, location based content recommendation scheme is proposed, verified by simulation.

The core problems of database migration are the data integrity, data accuracy and business continuity. We discussed these problems during heterogeneous database migration in this article. We designed and implemented a migration project for Tsinghua University. This project migrated Oracle RAC into a heterogeneous database completely and successfully.

Database migration may affect the running of the information system. And the integrity, veracity and business continuity are the difficult problems in the process. We discussed the business continuity in this article. New and old concomitant network environment is constructed at the same time. Voting disk, ocr (Oracle Cluster Registry) and ASM data are migrated stage by stage online. We made zero-downtime database migration and completed the core database migration which supported the teaching, research, IC card and etc. in university. And also it didn't interrupt or affect the information system in the whole process.

We make an investigation into the approach and technique used in database Migration in this paper. Different database migrations such as Oracle, SqlServer are discussed. As an example, we design and implement a migration project for Tsinghua University. This project migrates Oracle RAC into a different platform completely and successfully. At the same time, it will shorten the switch time and minimize the influence.

After many years of information technology, it is urgent for each university to eliminate “Information Islands” and achieve data sharing and exchanging during information system construction. In this paper, the author researched into data share and exchange technique, designed and executed university data sharing and exchanging platform based on trigger, privilege, ETL and ESB, presented a technique selection method matching requirement and performance, well achieved more than 1000 data sharing and exchanging among more than 20 departments and 50 information systems, and thus get the aimed results.

In order to solve the problem of different data formats in E-Learning Standard Test System, this paper translates each CELTS sub-standard from their own natural language format into XML schema document. The author writes out an independent XML parsing and validating package, which can automatically build up an internal data structure from each translated XML schema document. The author uses this private data structure to validate the XML data document. This innovation is applied in E-Learning standard test system successfully. It makes the whole test system more rigorous and maintainable.

For the universities' business system, to realize secure storage of historical data and long-term retention, saving high-end storage, online database backup pressure relief. A record-level data archiving method was proposed based on oracle dual database structure. This method included three aspects: related works, related technologies and strategy on data archive. For universities' business system, analysis of some problems need to concern and solution when the data archive, included four aspects: business analysis, storage analysis, data analysis and technical analysis. Finally, effectiveness of this method was validated by an application example in Tsinghua University. Index Terms—information flow, data management, data archiving, hierarchical storage management

To solve data exchange problems among heterogeneous databases in university data sharing platform, in this paper, the author focused on further research on Extract Transform Load (ETL) technology, designed and executed university data sharing platform based on CloverETL. This module, the core of the whole university data exchange platform, can well achieve data exchange and sharing among heterogeneous databases and run stably with less influence on server and business system, and thus getting a better result.