Evaluation of Natural Radioactivity in Marine Sand Deposits from Offshore China

Natural radioactivity is very important for the assessment of the marine sand property and usability. By using gamma spectrometry, the concentration of the natural radionuclides 226Ra, 232Th and 40K have been measured in marine sand deposits from Liaodong Bay (LDB), North Yellow Sea (NYS), Zhoushan area (ZS), Taiwan Shoal (TS) and Pearl River Mouth (PR), offshore China, which are potential marine sand mining areas. The radiation activity equivalent (Raeq), indoor gamma absorbed dose rate (DR), annual effective dose (HR), alpha index (Ia), gamma index (Ig), external radiation hazard index (Hex), internal radiation hazard index (Hin), representative level index (RLI), excess lifetime cancer risk (ELCR) and annual gonadal dose equivalent (AGDE) associated with the natural radionuclides are calculated to assess the radiation hazard of the natural radioactivity in the marine sands offshore China. From the analysis, it is found that these marine sands are safe for the constructions. The Pearson correlation coefficient reveals that the 226Ra distribution in the marine sands offshore China is controlled by the variation of the 40K concentration. Principal component analysis (PCA) yields a two-component representation of the entire data from the marine sands, wherein 98.22% of the total variance is explained. Our results provide good baseline data to expand the database of radioactivity of building materials in China and all over the world.

Multi-channel DMA Based Design of Voltage Monitoring Using Synchronous Frequency Trace-Sampling Technique

In order to eliminate the influence of frequency change on real-time voltage acquisition,a low-cost solution of voltage monitoring was proposed using the multi-channel DMA synchronous frequency trace-sampling technique.In-chip resources of the designed voltage monitor were fully utilized in hardware design to reduce external devices.The MQX RTOS was used to perform the functional tasks flexibly and efficiently;especially the Ethernet communication applications and USB device connection were realized using its TCP/IP protocol stack and USB driver.In addition,to ensure the safety of electrical records,data statistics and alarm information management were also implemented through the management of the storage in FLASH.The test results show that the voltage monitor designed in this paper has the advantages of accurate measurement,strong resistance to frequency interference and low cost,and can be widely applied in the field of voltage monitoring in distribution networks.

A validated reversed phase HPLC method for determination of process-related impurities in DHDK-loaded mPEG-PLA micelles

A new compound named DHDK was isolated from Viscum coloratum and identified as (1E,4E)-1,7-bis(4-hydroxyphenyl)hepta -1,4-dien-3-one. DHDK, a new potential anti-tumor drug, was synthesized and prepared poly(ethylene glycol)-poly(D.L-lactic acid)(mPEG-PLA) micelles due to cytotoxic effects on a range of cancer cells. A revered phase liquid chromatographyic method has been developed and validated for the determination of potential related impurities in DHDK-loaded mPEG-PLA micelles. The micelles was subjected to the stress conditions of acid, base, oxidation, thermal and photolysis. The determination was achieved on Phenomenex SynergiTM 4 μm Fusion-RP 80?(250 mm × 4.6 mm, 4 μm) with a gradient elution and the detection wavelength was set at 220 nm. Regression analysis shows as r value (correlation coefficient) of greater than 0.999 for DHDK and six potential impurities. Recoveries of impurities were found between 90.0% and 108.0%. The developed RP-LC method was validated with respect to linearity, accuracy, precision and robustness, which can be used for determination of related impurities in DHDK-loaded mPEG-PLA micelles.

Mechanism Design for Ancillary Service Market Considering Social Welfare and Fairness

Increasing penetration of distributed energy resources in the distribution network(DN)is threatening safe operation of the DN,which necessitates setup of the ancillary service market in the DN.In the ancillary service market,distribution system operator(DSO)is responsible for safety of the DN by procuring available capacities of aggregators.Unlike existing studies,this paper proposes a novel market mechanism composed of two parts:choice rule and payment rule.The proposed choice rule simultaneously considers social welfare and fairness,encouraging risk-averse aggregators to participate in the ancillary service market.It is then formulated as a linear programming problem,and a distributed solution using the multi-cut Benders decomposition is presented.Moreover,successful implementation of the choice rule depends on each aggregator’s truthful adoption of private parameters.Therefore,a payment rule is also designed,which is proved to possess two properties:incentive compatibility and individual rationality.Simulation results demonstrate effectiveness of the proposed choice rule on improving fairness and verify properties of the payment rule.

Multi-stage Co-planning Model for Power Distribution System and Hydrogen Energy System Under Uncertainties

The increased deployment of electricity-based hydrogen production strengthens the coupling of power distribution system(PDS)and hydrogen energy system(HES).Considering that power to hydrogen(PtH)has great potential to facilitate the usage of renewable energy sources(RESs),the coordination of PDS and HES is important for planning purposes under high RES penetration.To this end,this paper proposes a multi-stage co-planning model for the PDS and HES.For the PDS,investment decisions on network assets and RES are optimized to supply the growing electric load and PtHs.For the HES,capacities of PtHs and hydrogen storages(HSs)are optimally determined to satisfy hydrogen load considering the hydrogen production,tube trailer transportation,and storage constraints.The overall planning problem is formulated as a multistage stochastic optimization model,in which the investment decisions are sequentially made as the uncertainties of electric and hydrogen load growth states are revealed gradually over periods.Case studies validate that the proposed co-planning model can reduce the total planning cost,promote RES consumption,and obtain more flexible decisions under long-term load growth uncertainties.

Next generation lanthanide doped nanoscintillators and photon converters

Scintillators are of significance for the realization of indirect X-ray detection and X-ray excited optical luminescence(XEOL)imaging.However,commercial bulk scintillators not only require complex fabrication procedures,but also exhibit non-tunable XEOL wavelength and poor device processability.Moreover,thick crystals usually generate light scattering followed by evident signal crosstalk in a photodiode array.Lanthanide doped fluoride nanoscintillators(NSs)prepared with low-temperature wet-chemical method possess several advantages,such as low toxicity,cheap fabrication cost,convenient device processability and adjustable emission wavelengths from ultraviolet to visible and extending to second near infrared window.In addition,they exhibit X-ray excited long persistent luminescence(XEPL)making them suitable for broadening the scope of their applications.This review discusses and summarizes the XEOL and XEPL characteristics of lanthanide doped fluoride NSs.We discuss design strategies and nanostructures that allow manipulation of excitation dynamics in a core-shell geometry to simultaneously produce XEOL,XEPL,as well as photon upconversion and downshifting,enabling emission at multiple wavelengths with a varying time scale profile.The review ends with a discussion of the existing challenges for advancing this field,and presents our subjective insight into areas of further multidisciplinary opportunities.

Sunlight activated ultra-stable long persistent luminescence glass ceramic for outdoor information display

Natural sunlight activated persistent luminescence(PeL)is ideal candidate for optical information display in outdoors without the requirement of electric supply.Except the brightness and duration,the stability especially water resistance of the PeL materials is of significant importance for practical application,which remains a great obstacle up to date.Herein,we report a new sunlight activated PeL glass ceramic containing hexagonal Sr_(13)Al_(22)Si_(10)O_(66):Eu^(2+)crystals,which exhibits strong blue PeL and can last more than 200 h.The PeL can be charged by the full wavelengths located in AM 1.5G due to the broad distribution of traps in the crystal structure.The PeL is clearly observed by the naked eye even after 24 h upon sunlight irradiation irrespective of the weather,and the photoluminescence intensity only decreased~3.3%after storing in water for 365 d.We demonstrate its potential application for thermal and stress responsive display as well as long-term continuous security indication upon sunlight irradiation,which not only save vast energy and reduce environment pollution,but also are appropriate for outdoor usage.

Optimal Operation Control Strategies for Active Distribution Networks Under Multiple States:A Systematic Review

With the large-scale integration of distributed renewable generation(DRG)and increasing proportion of power electronic equipment,the traditional power distribution network(DN)is evolving into an active distribution network(ADN).The operation state of an ADN,which is equipped with DRGs,could rapidly change among multiple states,which include steady,alert,and fault states.It is essential to manage large-scale DRG and enable the safe and economic operation of ADNs.In this paper,the current operation control strategies of ADNs under multiple states are reviewed with the interpretation of each state and the transition among the three aforementioned states.The multi-state identification indicators and identification methods are summarized in detail.The multi-state regulation capacity quantification methods are analyzed considering controllable resources,quantification indicators,and quantification methods.A detailed survey of optimal operation control strategies,including multi-state operations,is presented,and key problems and outlooks for the expansion of ADN are discussed.