Research on Time Delay of Control in Hybrid Vibration Isolation System

AbstractThe asymptomatic stability problem of robust with time lag is widely existed in active vibration isolation system. The influence of time lag on the optimal control algorithm is studied in this paper. And by utilizing LMI tools in MATLAB, variable step method is introduced to get the maximum allowable upper bound of the robust time lag in the optimal control system. Numerical simulation results verified the theory and contributed to the conclusion that with time lag increasing, the effect of controlling will become worse,once the time lag exceed the maximum allowable delay boundary, the system will diverge.At the same time,the upper bound can be improved by increasing feedback control and decreasing the corresponding weight of the control goals weighting matrix. The work of this paper is beneficial for the relevant experimental design

Derivation of aquatic life criteria for four phthalate esters and their ecological risk assessment in Liao River

As a critical family of endocrine disruptors, phthalate esters (PAEs) attracted considerable attentions due to increasingly detected worldwide. Aquatic life criteria (ALC) for PAEs are crucial for their accurate ecological risk assessment (ERA) and have seldom been derived before. Given this concern, the purpose of the present study is to optimize the ALCs of four priority PAEs to estimate their ecological risks in Liao River. Reproductive endpoint was found to be more sensitive than other endpoints. Thus, reproduction related toxicity data were screened to derive ALCs applying species sensitivity distribution (SSD) method. ALCs of DEHP, DBP, BBP and DEP were calculated to be 0.04, 0.62, 4.71 and 41.9 μg L−1, which indicated decreased toxicity in sequence. Then, the derived ALCs of the four PAEs were applied to estimate their ecological risks in Liao River. A total of 27 sampling sites were selected to detect and analyze the exposure concentrations of PAEs. ERA using the hazard quotient (HQ) method was conducted. The results demonstrated that DEHP exhibited higher risks at 92.6% of sampling sites, and risks posed by DBP were moderate at 63.0% sampling sites. However, risks posed by BBP were low at 70.4% of sampling sites, and there were no risks posed by DEP at 96.3% of sampling sites. The results of probabilistic ecological risk assessment (PERA) indicated that probabilities of exceeding effects thresholds on 5% of species were 60.41%, 0%, 0.12%, 14.28% for DEHP, DEP, BBP and DBP, respectively. The work provides useful information to protect aquatic species in Liao River

Anti-oxidative effects of the biennial flower of Panax notoginseng against H2O2-induced cytotoxicity in cultured PC12 cells

<p>Abstract</p> <p>Background</p> <p><it>Radix notoginseng </it>is used in Chinese medicine to improve blood circulation and clotting; however, the pharmacological activities of other parts of <it>Panax notoginseng </it>have yet to be explored. The present study reports the anti-oxidative effects of various parts of <it>Panax notoginseng</it>.</p> <p>Methods</p> <p>Various parts of <it>Panax notoginseng</it>, including the biennial flower, stem-leaf, root-rhizome, fiber root and sideslip, were used to prepare extracts and analyzed for their anti-oxidation effects, namely suppressing xanthine oxidase activity, H₂O₂-induced cytotoxicity and H₂O₂-induced ROS formation.</p> <p>Results</p> <p>Among various parts of the herb (biennial flower, stem-leaf, root-rhizome, fiber root and sideslip), the water extract of the biennial flower showed the strongest effects in (i) inhibiting the enzymatic activity of xanthine oxidase and (ii) protecting neuronal PC12 cells against H₂O₂-induced cytotoxicity. Only the water extracts demonstrated such anti-oxidative effects while the ethanol extracts did not exert significant effects in suppressing xanthine oxidase and H₂O₂-induced neuronal cytotoxicity.</p> <p>Conclusions</p> <p>The present study demonstrates the biennial flower of <it>Panax notoginseng </it>to have neuroprotection effect on cultured neurons and the underlying protection mechanism may involve anti-oxidation.</p

Two TPX2-Dependent Switches Control the Activity of Aurora A

Aurora A is an important oncogenic kinase for mitotic spindle assembly and a potentially attractive target for human cancers. Its activation could be regulated by ATP cycle and its activator TPX2. To understand the activation mechanism of Aurora A, a series of 20 ns molecular dynamics (MD) simulations were performed on both the wild-type kinase and its mutants. Analyzing the three dynamic trajectories (Aurora A-ATP, Aurora A-ADP, and Aurora A-ADP-TPX2) at the residue level, for the first time we find two TPX2-dependent switches, i.e., switch-1 (Lys-143) and switch-2 (Arg-180), which are tightly associated with Aurora A activation. In the absence of TPX2, Lys-143 exhibits a “closed” state, and becomes hydrogen-bonded to ADP. Once TPX2 binding occurs, switch-1 is forced to “open” the binding site, thus pulling ADP away from Aurora A. Without facilitation of TPX2, switch-2 exits in an “open” conformation which accompanies the outward-flipping movement of P·Thr288 (in an inactive conformation), leading to the crucial phosphothreonine exposed and accessible for deactivation. However, with the binding of TPX2, switch-2 is forced to undergo a “closed” movement, thus capturing P·Thr288 into a buried position and locking its active conformation. Analysis of two Aurora A (K143A and R180A) mutants for the two switches further verifies their functionality and reliability in controlling Aurora activity. Our systems therefore suggest two switches determining Aurora A activation, which are important for the development of aurora kinase inhibitors

Ensuring water resource security in China; the need for advances in evidence based policy to support sustainable management.

China currently faces a water resource sustainability problem which is likely to worsen into the future. The Chinese government is attempting to address this problem through legislative action, but faces severe challenges in delivering its high ambitions. The key challenges revolve around the need to balance water availability with the need to feed a growing population under a changing climate and its ambitions for increased economic development. This is further complicated by the complex and multi-layered government departments, often with overlapping jurisdictions, which are not always aligned in their policy implementation and delivery mechanisms. There remain opportunities for China to make further progress and this paper reports on the outcomes of a science-to-policy roundtable meeting involving scientists and policy-makers in China. It identifies, in an holistic manner, new opportunities for additional considerations for policy implementation, continued and new research requirements to ensure evidence-based policies are designed and implemented and identifies the needs and opportunities to effectively monitor their effectiveness. Other countries around the world can benefit from assessing this case study in China

Efficient Coding-Based Scheduling for Multi-Item Requests in Real-Time On-Demand Data Dissemination

On-demand broadcast is an effective data dissemination technique to enhance the system ability to handle dynamic client access patterns. With the development of real-time wireless applications, it is practical for clients to request multiple related data items with time constraint in one request. For real-time data broadcast, items are only useful if they can be received by clients before expiration; otherwise, the related requests become invalid. Hence, minimizing the number of requests that miss their deadlines becomes an important task in on-demand broadcast, especially for multi-item scenario, where more requests are inclined to miss their deadlines due to the heavier workload and greater complexity, compared with single-item scenario. In this paper, we propose a network coding-based scheduling algorithm for real-time multi-item data dissemination. The proposed algorithm exploits the coding opportunities between cached and requested data items and integrates network coding with data scheduling to minimize the deadline miss ratio. Extensive simulation results demonstrate that the proposed algorithm achieves the lowest deadline miss ratio under various circumstances. In addition, the high efficiency of the proposed algorithm in utilizing the transmission bandwidth is proved for that fewer instances of ineffective service are provided for satisfying clients’ requests within time constraints

Evaluation of the performance of ventilative cooling systems with different control parameters

To evaluate the performance and energy savings of different ventilative cooling systems, three mixed forms of ventilative cooling were described and the most promising rule-based heuristic control criteria were used as applicable control strategies based on various control parameters. Parametric analyses including the ventilative cooling set-points and control frequencies have been conducted. EnergyPlus was used to perform the aforementioned analyses based on a typical office building. Case studies verified that the use of different control parameters led to different indoor air environment and energy performance in a certain climatic zone. Then, the percentages outside the range indexes (POR) of the three mixed forms of ventilative cooling with various control parameters in five representative climatic zones in China were calculated, the results demonstrated that the ventilative cooling performance was mainly related to the ventilative cooling form in HSCW, HSWW, and temperate climatic zones. While in cold and severe cold climatic zones, it was mainly affected by selection of control parameters and its corresponding set-points. It can provide guidance for the selection of ventilative cooling scheme capable of maintaining indoor environment level with a low energy consumption in different climatic zones of China

Exploration of Copula Models Use in Risk Assessment for Freezing and Snow Events: A Case Study in Southern China

Due to cold waves, low and extremely low temperatures occur every winter. Sudden cooling can cause freezing and snow disasters, which seriously affect transportation, power, safety, and other activities, resulting in serious economic losses. Based on precipitation and average temperature data from 258 national meteorological stations over the past 70 years, this study established a historical freezing and snow event data set, extracting the accumulated precipitation intensity (API) and accumulated temperature intensity (ATI). We selected the optimal distribution function and joint distribution function for each station and calculated the univariate and bivariate joint return periods. The return period accuracy plays an important role in risk assessment results. By comparing the calculations with the real return period for historical extreme events, we found that the bivariate joint return period based on a copula model was more accurate than the univariate return period. This is important for the prediction and risk assessment of freezing and snow disasters. Additionally, a risk map based on the joint return period showed that Jiangsu and Anhui, as well as some individual stations in the central provinces, were high-risk areas; however, the risk level was lower in Chongqing and the southern provinces

Variation in coumarin accumulation by stem age in Dendrobium thyrsiflorum (Orchidaceae) at different developmental stages

In this study, laser scanning confocal microscopy was applied to determine the localization and relative quantity of coumarins in stems of Dendrobium thyrsiflorum Rchb. f. (Orchidaceae) when plants enteredprofuse flowering and initial fruit period during reproductive growth stage. Stems at the two growth stages were collected respectively. Distribution of coumarins in the top, middle and basal parts of eachstem sample of 1, 2 and 3-year-old were observed by laser scanning confocal microscope. ANOVA and Tukey’s test were employed in the statistical analyses. The results showed that coumarins was locatedmainly in vascular bundle and its outer fiber cell wall, ground tissue cell wall and nearby, wall of epidermal cell and hypodermis cell as well. Statistical analyses indicated the significant or great significant difference presented in every part of stem of different ages in different growth periods except in the middle part during profuse flowering time. The content of coumarins reached its highest level when flowers profuse whereas at initial fruit stage that of coumarins was the lowest. Harvest activities of D. thyrsiflorum should be carried out when plants entered profuse flowering period in order to obtain abundant courmarins