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The nondestructive assessment of nitrogen status in strawberry was performed to analyze its growth and provide guidance for precise management of N fertilizer using Fourier transform near-infrared reflectance (FT-NIR) spectroscopy with leaf spectral reflectance. The leaf soil plant analysis development (SPAD) value is considered as an indicator that indirectly reflects the nitrogen status in strawberry. However, the variation of cultivars leads to differences in the cell structure and light scattering and/or reflection effects of strawberry leaves during strawberry N status assessment, which means, leaf SPAD threshold value and the specific N demand will vary with different cultivars. As a result, accurate measurement of SPAD values and N status in strawberries with multiple cultivars is still challenging. In this study, the individual-cultivar, hybrid-cultivar, and multi-cultivar models were developed for the determination of SPAD values, and the performance of the models in lessening the impact of cultivar variation was studied and compared. The individual-cultivar model was constructed on the basis of a single cultivar of strawberry leaf. The hybrid-cultivar model was developed by merging the spectrum reflectance data and SPAD values of all studied leaf samples, and a multi-cultivar model was built in combination with cultivar identification, individual-cultivar models, and model search strategy. The results indicated that the multi-cultivar model was superior to the other two models for SPAD value estimation of strawberry leaves from different cultivars, with the overall Rp and RMSEP values of 0.966 and 0.468, respectively. We demonstrate that the leaf N content of strawberry is profoundly affected by cultivar variation, and establishing a multi-cultivar model is useful in monitoring the nitrogen status and guiding N fertilization recommendations for different strawberry cultivars.

Manipulation of group-velocity-locked vector solitons (GVLVSs) is numerically proposed and experimentally demonstrated. A pseudo-high-order GVLVS could be generated from a fundamental GVLVS with the help of a polarization-resolved system. Specifically, a pseudo-high-order GVLVS with a two-humped pulse along one polarization and a single-humped pulse along the orthogonal polarization could be obtained. The phase difference between the two humps could be 180°.

We demonstrate a wavelength tunable dual-wavelength fiber laser using black phosphorus (BP) saturable absorber. By controlling the tunable filter together with a polarization controller to adjust intra-cavity birefringence, dual-wavelength pulses tunable from 1532 nm to 1545 nm are observed.

Pseudo-high-order group-velocity-locked vector dissipative soliton (GVLVDS) from a normal-dispersion fiber laser is achieved. It has a two-humped temporal profile along one polarization direction, while single-humped along the orthogonal polarization. The contribution of the strong frequency chirp for the structure is first experimentally demonstrated.

As CMOS technology scales, the Increasingly smaller transistor components are susceptible to a variety of in-field hardware errors. Traditional redundancy techniques to deal with the increasing error rates are expensive and energy inefficient. To address this emerging challenge, many researchers have recently proposed the idea of relaxed hardware design and exposing errors to software. For such relaxed hardware to become a reality, it is crucially important for system software, such as the virtual machine hypervisor, to be resilient to hardware faults. To address the above fundamental software challenge in enabling relaxed hardware design, we are making a major effort in restructuring an important part of system software, namely the virtual machine hypervisor, to be resilient to faulty cores. A fault in a relaxed core can only affect those virtual machines (and applications) running on that core, but the hypervisor and other virtual machines remain intact and continue providing services. We have redesigned every component of Xen, a large, popular virtual machine hypervisor, to achieve such error resiliency. This paper presents our design and implementation of the restructured Xen (we refer to it as FTXen). Our experimental evaluation on real systems shows that FTXen adds minimum application overhead, and scales well to different ratios of reliable and relaxed cores. Our results with random fault injection show that FTXen can successfully survive all injected hardware faults.

When we evaluate the value of the enterprise by using two-stage discounted cash flow model, it is difficult to divide the period of rapid development and the period of stable development, lots of factors affect the cut-off point, so the cut-off point is uncertain. The purpose of this paper is to settle the uncertain cut-off point. We combine the fuzzy theory with the two-stage discounted cash flow model; the uncertainties of the cut-off point are fuzzified by the trapezoidal fuzzy number. Finally, we get the modified discounted cash flow model.

In this paper, we build an electric vehicle's time-series model of patent technology based on the analysis patent data, conducting to the status and trends of electric vehicle's patent applications; based on the patent applications in the related fields, time and the applicant and the International Patent Classification corresponding analysis, we research and predict the priority areas of electric vehicles' patent technology. In addition, we summarize the major routes of patent technology of some automotive manufacturers for the China's enterprises positioning in international competitiveness in the electric vehicle industry. Then they can use these as references to develop their own proprietary routes and adjust the direction of investment in patent technology.

Intel and AMD have provided hardware support, VT and SVM, to support classical full virtualization. The hardware extensions help to implement a VMM without changing the guest OS or resorting to software binary translation. Ironically, a VMM using VT or SVM has not yet met performance expectation. One major reason is that there still exist too many VM exits that incur significant overhead. This paper proposed a novel method, Competition in Bucket Method (CBM), to track all VM exits efficiently. The analysis and experiments show that, CBM can find out hot VM exits efficiently.

“Network Storage and System Virtualization Technologies” is an up-to-date course opened by the school of electronics engineering and computer science of Peking University. The purpose of this course is to help students to catch up with the fast development of computer science. The theory and the practice of the course mainly give emphasis on the design of “data center”, including “network storage” and “system virtualization”. In addition, this course sets up experiments related with virtualization, combining multicore technology and network storage technology.

In virtual machine (VM) systems, with the increase in the number of VMs and the demands of applications, the main memory is becoming a bottleneck of application performance. To improve paging performance for memory-intensive or I/O-intensive workloads, we propose the hypervisor REMOte disk CAche (REMOCA), which allows a virtual machine to use the memory resources on other physical machines as its cache between its virtual memory and virtual disk devices. The goal of REMOCA is to reduce disk accesses, which is much slower than transferring memory pages over modern interconnect networks. As a result, the average disk I/O latency can be improved. REMOCA is implemented within the hypervisor, by intercepting guest events such as page evictions and disk accesses. This design is transparent to the applications, and is compatible with existing techniques like ballooning and ghost buffer. Moreover, a combination of them can provide a more flexible resource management policy. Our experimental results show that REMOCA can efficiently alleviate the impact of thrashing behavior, and also significantly improve the performance for real-world I/O intensive applications.

Virtualization is often used in systems for the purpose of offering isolation among applications running in separate virtual machines (VM). Current virtual machine monitors (VMMs) have done a decent job in resource isolation in memory, CPU and I/O devices. However, when looking further into the usage of lower-level shared cache, we notice that one virtual machine’s cache behavior may interfere with another’s due to the uncontrolled cache sharing. In this situation, performance isolation cannot be guaranteed. This paper presents a cache partitioning approach which can be implemented in the VMM. We have implemented this mechanism in Xen VMM using the page coloring technique traditionally applied to the OS. Our VMM-based implementation is fully transparent to the guest OSes. It thus shows the advantages of simplicity and flexibility. Our evaluation shows that our cache partitioning method can work efficiently and improve the performance of co-scheduled applications running within different VMs. In the concurrent workloads selected from the SPEC CPU 2006 benchmarks, our technique achieves a performance improvement by up to 19% for the most sensitive workloads