Synthesis, characterisation and decomposition properties of manganese-based borohydrides for hydrogen storage

In this work, a series of Mn-based borohydrides were synthesized by mechanochemical milling of ABH$_4$-MnCl$_2$ (where A=Li, Na, K) under argon. Samples prepared by milling xLiBH$_4$-MnCl$_2$ (where x = 2 or 3) resulted in the formation of Mn(BH$_4$)$_2$ and LiCl in a stoichiometric ratio. Thermal decomposition of Mn(BH$_4$)$_2$ was observed between 105 and 180°C with the concurrent evolution of hydrogen and diborane. Analysis of the decomposition products suggested the presence of amorphous B, Mn and LiCl. When NaBH$_4$ was used as a reagent, Mn(BH$_4$)$_2$ was also observed, however instead of NaCl, a solid solution of NaCl$_x$(BH$_4$)$_1$$_-$$_x$ and Na$_6$MnCl$_8$ were formed. Mn(BH$_4$)$_2$ decomposed between 110 and 170°C for xNaBH$_4$-MnCl$_2$ with the concurrent evolution of hydrogen and diborane. Analysis of the decomposed samples showed that amorphous B and Mn formed (110 to 170°C) and NaCl$_x$(BH$_4$)$_1$$_-$$_x$ reacted with Na$6$MnCl$_8$ to produce NaCl (250 to 475°C). When KBH$_4$ was used as a reagent, Mn(BH$_4$)$_2$ was not observed. Rather, K$_2$Mn(BH$_4$)$_4$, KMnCl$_3$ and unreacted KBH$_4$ were observed. The mass losses for the milled sample were observed between 100 to 160°C with a release of hydrogen and trace diborane, forming KBH$_4$, B, and Mn, and between 165 to 260°C with only hydrogen release, giving KCl, B and Mn

Mn-based borohydride synthesized by ball-milling KBH4 and MnCl2 for hydrogen storage

AbstractIn this work, a mixed-cation borohydride (K2Mn(BH4)4) with P21/n structure was successfully synthesized by mechanochemical milling of the 2KBH4–MnCl2 sample under argon. The structural and thermal decomposition properties of the borohydride compounds were investigated using XRD, Raman spectroscopy, FTIR, TGA-MS and DSC. Apart from K2Mn(BH4)4, the KMnCl3 and unreacted KBH4 compounds were present in the milled 2KBH4–MnCl2. The two mass loss regions were observed for the milled sample: one was from 100 to 160 °C with a 1.6 ± 0.1 wt% loss (a release of majority hydrogen and trace diborane), which was associated with the decomposition of K2Mn(BH4)4 to form KBH4, boron, and finely dispersed manganese; the other was from 165 to 260 °C with a 1.9 ± 0.1 wt% loss (only hydrogen release), which was due to the reaction of KBH4 with KMnCl3 to give KCl, boron, finely dispersed manganese. Simultaneously, the formed KCl could dissolve in KBH4 to yield a K(BH4)xCl1−x solid solution, and also react with KMnCl3 to form a new compound K4MnCl6

Event-Triggered Reliable Control in Networked Control Systems with Probabilistic Actuator Faults

This paper introduces a novel event-triggered scheme into networked control systems which is used to determine when to transmit the newly sampled state information to the controller. Considering the effect of the network transmission delay and probabilistic actuator fault with different failure rates, a new actuator fault model is proposed under this event-triggered scheme. Then, criteria for the exponential mean square stability (EMSS) and criteria for codesigning both the feedback and the trigger parameters are derived by using Lyapunov functional method. These criteria are obtained in the form of linear matrix inequalities. A simulation example is employed to show that our event-triggered scheme can lead to a larger release period than some existing ones

Nationwide Assessment of Urban Surface Water Environment Status in China

In this study, the assessment of nationwide urban water environment status was conducted based upon a method of integrating both 70% of objective water quality and 30% of standard compliance percent compared with national standard limit of GB3838-2002 for Class III. The impact factors on urban water environment status were discussed. The results showed that the status of urban water environment could be graded into 5 types in China. The population density, water resources, urbanized areas and so on were key impact factors on water environment. The study found that population density and urban built-up area had significantly negative effect on urban water environment status, and there was positive relationship between per capita water resources and urban water environment status. The results would provide the guidance for effective governance and management of urban water environment at national level

A New Stochastic Geometry Model of Coexistence of Wireless Body Sensor Networks

Stochastic geometry, in particular Poission point process theory, has been widely used in the last decade to provide models and methods to analyze wireless networks. It is a branch of mathematics which deals with the study of random point processes. There are various models for point processes, typically based on but going beyond the classic homogeneous Poisson point process. Poisson point process cannot be used to model the spatial distribution of the simultaneously active transmitters. A novel framework has been presented for modeling the intensity of simultaneous active transmitters of a random carrier sense multiple access wireless sensor network. This thinning rule uses a second-neighbors distance-dependent method, which controls too many nodes deleted of points close together

A heterogeneous signcryption scheme for smart grid with trusted multi-ciphertext equality test

Energy utilization rates have been largely improved thanks to the wide application of smart grids, thereby realizing the reliable, economic and efficient operation of the grids. However, such an application is also accompanied by many security issues. In response to the many problems within existing security schemes, such as not supporting the communication between heterogeneous cryptosystems, low security levels and a low data retrieval efficiency, a heterogeneous signcryption (HSC) scheme that supports a trusted multi-ciphertext equality test (MET) is proposed. The adoption of the HSC helps to identify secure communications from identity-based cryptosystems to certificateless cryptosystem, eliminates the certificate management problems in the traditional public key cryptography scheme, and ensures the confidentiality and authentication of power data. The introduction of the MET technology can avoid the high cost of equality test calculations after grouping ciphertexts in pairs. Using blockchain and smart contract technologies ensure the credibility of test results and eliminates the reliance on trusted cloud servers. Under the random oracle model, on the basis of the bilinear Diffie-Hellman, the computational Diffie-Hellman and the q-strong Diffie-Hellman problems, this paper proves that the scheme proposed herein meets the requirements of indistinguishability and one-way security under adaptive choice ciphertext attacks, and the unforgeability under the adaptive choice message attack. From the findings of the analysis, it has been shown that the proposed scheme satisfies more security attributes and requires lower computational overhead compared to similar schemes