High-capacity Systems Research Articles

A high-capacity hybrid desalination system using battery type and pseudocapacitive type electrodes

A membrane-free hybrid system employing the battery-type copper hexacyano-ferrate (CuHCF) and the pseudocapacitive polypyrrole (PPy) as the positive and negative electrodes are designed for faradaic desalination. Both materials exhibit a memory effect, a unique characteristic of the faradaic reaction, with the dual function of ion removing and concentrating. The appropriate mass ratio of two materials is adjusted according to the positive/negative charge balance to ensure that both electrodes work in their respectively suitable potential windows. Through the little inverted voltage (−0.2 V) during the discharge process in order to keep the two electrodes in the desirable potential windows in comparison with the case discharged at 0 V, the salt removal capacity (SRC) of this hybrid system is significantly increased from 21.17 mg g−1 to 26.62 mg g−1 in 8 mM NaCl. Under this operation condition, the cell keeps >90 % of the original SRC in a 100-cycle stability test. The SRC obtained in 8 mM NaCl solution can increase to 38.64 mg g−1 after employing the acid-treated CNT/CuHCF composite. The system also exhibits superior performance on removing other cations including K+, Mg2+, and Ca2+. All results reveal the promising application potential of this system to the faradaic desalination and metal-ion concentrating and recovering.

Experimental Research on Heat Transfer Performance of CO2 Tube Bundle Falling Film Evaporator

Abstract CO2 is a promising refrigerant substitute, and falling film evaporator is widely used in high-capacity heat pump systems. In this article, a CO2 heat pump experimental device is built. According to experimental parameters, a CO2 falling film heat exchanger is fabricated. The falling film heat exchanger is used in heat pump evaporator, and its heat transfer characteristics are analyzed and tested. The outer diameter of the heat exchanger is 219 mm, outer diameter of the inner tube is 15.88 mm, and total outer surface area of the inner tube is 0.58 m2. Number of internal tubes was 12, each with a length of 0.97 m. During the test, change of heat transfer coefficient of each tube was analyzed when evaporation temperature, CO2 mass flowrate, and heat flow density changed. The influence of the position of heat exchange tube inside falling film evaporator on heat transfer coefficient is analyzed. The order of heat transfer coefficient of internal heat exchange tube is obtained. Finally, database of CO2 falling film evaporator is established. Through data sorting, heat exchange correlation formula is obtained. The deviation of 90% data in database is less than 5%. Heat exchange correlation formula has good accuracy.

High-order orbital angular momentum mode conversion based on a chiral long period fiber grating inscribed in a ring core fiber.

A chiral long period fiber grating (CLPFG) was designed according to the phase-matching condition and conservation law of angular momentum, and was inscribed in a ring core fiber (RCF). This CLPFG was used to directly excite the ±2nd- and ±3rd-order orbital angular momentum (OAM) modes. The coupling efficiency of the OAM mode is up to 98.7% and the insertion loss is within 0.5 dB. The uniformity of the annular mode intensity distribution, polarization characteristics, and the mode purity of coupled OAM modes were investigated in detail. Results show that the coupled high-order OAM modes possess a relative uniform annular intensity distribution, its mode purity is up to 93.2%, and the helical phase modulation is independent on the polarization state of incident light. These results indicate that the RCF-based CLPFG is an ideal OAM mode converter for future high-capacity optical fiber communication systems.

Antimony Telluride Nanocomposite As a High Performance Anode for Rechargeable Potassium-Ion Batteries

The development of high-capacity and low-cost energy storage systems are a top priority in electric vehicles and smart grids. Room temperature potassium-ion batteries (PIBs), which have the advantages of high theoretical capacity, abundant earth reserves, and low potassium costs, have recently emerged as an appealing alternative to traditional lithium-ion batteries (LIBs). In particular, finding advanced anode materials with suitable operation potential and high capacity is of significance for next-generation PIBs. In this regard, Sb-based materials have recently gained popularity as promising anode materials for batteries in terms of their suitable working potential, high density, and theoretical capacity. Among them, Sb2Te3 has a much higher density (6.66 g/cm3) than other Sb-based materials such as Sb2O3, Sb2S3, and Sb2Se3. This suggests that Sb2Te3 can have a high theoretical capacity. In addition, Te exhibits a higher conductivity than S or Se. Accordingly, the Sb2Te3 is appealing as an ideal anode for PIBs. Unfortunately, the Sb2Se3 has poor cycling stability and rate performances, which is primarily owing to the large volume change during alloying and dealloying.In this study, using a simple hydrothermal strategy, we synthesized a carbon-coated Sb2Te3 nanocomposite (Sb2Te3@C). In the novel design, the Sb2Te3@C nanocomposite is compactly encapsulated by a uniform carbon layer, which effectively relieves structural stress leading to preventing structural pulverization and stabilize the solid electrolyte interface layer. As expected with this optimal design, the Sb2Te3@C nanocomposite electrode performed nicely suitable for PIBs. In addition, the effect of the alloying/dealloying process on the crystal structure of Sb2Te3@C was investigated using in- situ/ex-situ XRD patterns recorded at various stages of discharge and charge to clarify the alloying mechanism. Furthermore, a full cell made up of a Sb2Te3@C anode and a potassium Prussian blue type cathode also exhibited successful operation.

A Joint Hybrid Precoding/Combining Scheme Based on Equivalent Channel for Massive MIMO Systems

Due to its inherent ability in reducing hardware cost and power consumption while maintaining high system capacity, hybrid precoding is deemed as one of the key technologies in the upcoming 5G/6G millimeter-wave (mmWave) massive multiple-input multiple-output (MIMO) systems. However, it is challenging to design high performance hybrid precoders/combiners with low computational complexity. In this paper, based on the singular value decomposition (SVD) technique and the concept of equivalent channel, joint hybrid precoding strategies with high spectral-efficiency and low complexity are proposed for both single-user and multi-user massive MIMO systems. Specifically, for single-user massive MIMO scenarios, after transforming the design of hybrid beamforming into the problem of maximizing the square of sum eigenvalues for an equivalent channel, a two-stage successive method is conceived to design the analog precoder and combiner jointly, and the corresponding equivalent channel is constructed. Then, the digital precoding and combining operations are realized directly by applying the SVD technique to the matrix of equivalent channel. Meanwhile, the hybrid precoding strategy is extended to the multi-user scenario for achieving high performance resultant from multi-user diversity. Extensive simulations are conducted to verify the effectiveness of the precoding/combing schemes. The results show that our proposed schemes can achieve superior performance with lower complexity compared to the existing ones.

Developing Adaptive Antennas for High-Capacity Communication Systems and Tracking Multiple Cellular Phones

In the lower microwave region, researchers are looking into solutions to overcome the problem of a crowded spectrum and limited accessible bandwidth. Researchers have recently devised systems that use directional antennas to overcome the problem of restricted channel bandwidth by combining sector beams from multiple directional antenna elements. By boosting channel capacity, enhancing spectral efficiency, extending range coverage, customizing beam shapes, and allowing multiple beams to steer to detect and track numerous mobile users, this strategy increases system performance. This study assumes and discusses a strategy for creating numerous beams. The goal is to build a physical representation of the cellular phone network. It is suggested that a beam guiding algorithm be used.

Spectral shaped PAM4 signal based on nonlinear differential coding for AOWC system with Self-pumping structure

Spectral shaped 4-level pulse amplitude modulation (PAM4) signal based on nonlinear different coding (NLDC) is proposed in an all-optical wavelength conversion (AOWC) system with self-pumping structure. Laser-driven Mach-Zehnder modulator generates multiple spectra and forms self-pumping structure by selecting signal and pump light, which can ignore the laser phase conversion noise. However, uniform PAM4 signal is severely distorted by nonlinear effects of the practical bandwidth-limited and power-limited AOWC systems. In order to effectively reduce nonlinear interference and fully evaluate the performance of the AOWC systems with self-pumping structure, the PAM4 signal based on NLDC is proposed and demonstrated in two AOWC systems based on parallel pump and vertical pump structures. Compared with the uniform PAM4 signal, the bit error rate (BER) of converted light with NLDC can be reduced by two orders of magnitude, two pump structures can reach 3.496 × 10−5 and 2.85 × 10−4, respectively. The two structures can obtain bandwidth tolerance gains of 3.45 GHz and 3.7 GHz, respectively. When the bandwidth is 18 GHz, this scheme can obtain more than 10Gbit/s data rate gain. In addition, NLDC can make PAM4 signal insensitive to the injection current of semiconductor optical amplifier, which proves that the proposed scheme has high tolerance to the nonlinear effect and is suitable for high-capacity AOWC system.

Potential for prediction of psychosis and bipolar disorder in Child and Adolescent Mental Health Services: a longitudinal register study of all people born in Finland in 1987.

Current strategies to predict psychosis identify only a small proportion of individuals at risk. Additional strategies are needed to increase capacity forpre-diction and prevention of serious mental illness, ideally during childhood and adolescence. One possible approach would be to investigate systems in which psychosis risk factors are concentrated during childhood. One notable such system is represented by Child and Adolescent Mental Health Services (CAMHS). Although psychotic disorders are uncommon in CAMHS, many risk factors for psychosis are highly prevalent in young people who enter this system. We hypothesized, therefore, that youth attending CAMHS would be a high-risk group for psychosis if followed into adulthood and, furthermore, that CAMHS systems would capture a substantial proportion of future psychosis cases. We constructed a total population cohort study of all Finns born in 1987 (N=55,875), linking together extensive register data on health care contacts from birth through age 28years. We identified all individuals diagnosed with a psychotic or bipolar disorder by age 28 (N=1,785). The risk of psychosis/bipolar disorder by age 28years was 1.8% for individuals who had not attended CAMHS during childhood or adolescence, whereas it was 12.8% for those with a history of any outpatient CAMHS contact (odds ratio, OR=7.9, 95% CI: 7.2-8.7). Furthermore, the risk of psychosis/bipolar disorder by age 28years was 2.3% for individuals without a history of inpatient CAMHS admission, whereas it was 24.0% for those with a history of inpatient CAMHS admission (OR=13.3, 95% CI: 11.9-14.9), and 36.5% for those with a history of inpatient CAMHS admission in adolescence (age 13-17years) (OR=24.2, 95% CI: 21.2-27.6). Individuals who attended CAMHS but received no mental disorder diagnosis had an equally high risk of subsequently developing a psychosis/bipolar disorder as individuals who did receive a diagnosis (OR=0.9, 99.5% CI: 0.7-1.1). Compared to other CAMHS attendees, individuals who developed psychosis or bipolar disorder were more likely to have had an initial CAMHS diagnosis of depressive or other mood disorder (OR=2.3, 99.5% CI: 1.6-3.0) and disruptive behaviour disorder (OR=1.7, 99.5% CI: 1.2-2.5). Of all psychosis/bipolar diagnoses by age 28years, 50.2% occurred in individuals who had, at some point in childhood or adolescence, attended CAMHS, indicating that CAMHS represent not only a high-risk but also a high-capacity system for prediction of psychosis/bipolar disorder. These findings suggest an enormous, untapped potential for large-scale psychosis/bipolar disorder prediction and prevention research within existing specialist CAMHS.

A Long-Life, High-Capacity and High-Efficiency Cryogenic System Developed for High-Tc Superconducting Magnet Applications

Cryogenic system plays a vital role in the field of high-Tc superconducting (HTS) magnet applications. For a variety of HTS magnet applications in energy storage devices, current limiters, generators, and maglevs, the technology itself is relatively mature. However, the problems associated with the used cryocoolers have hampered the advancement of their practical applications. At present, China is developing a new generation of electrodynamic suspension prototype train with HTS magnets. Compared with the existing commercial electromagnetic suspension technology, it has better suspension stability, larger suspension gap, and lower energy consumption. To meet the aimed cooling requirement of the vehicle-mounted HTS magnet, a long-life, high-capacity and high-efficiency cryogenic system based on the Stirling-type pulse tube cryocooler (SPTC) is designed and developed in the authors’ laboratory. The SPTC driven by the linear compressor without any moving component in the cold head has the intrinsic merits of long life and high reliability. The cryogenic system can achieve a minimum no-load cooling temperature of 12 K. Multiple SPTCs will provide a cooling capacity of 100 W at 45 K with the relative Carnot efficiency of 10.8 % to cool the HTS coils inside the magnet. This paper will describe and analyze the overall design approach, integration with the HTS magnet and the arrangement in maglev of the developed cryogenic system, together with the performance characteristics of the SPTC during the laboratory test.

Design and characteristics of ellipse-assisted ring-core fiber for space division multiplexing

• Elliptical-assisted ring-core fiber with central low-refractive-index elliptical region. • 9 effectively separated spatial modes have uniform Δn eff with values greater than 3.14 × 10 −4 at 1550 nm. • The level of polarization separation is lower than 3.33 × 10 −6 . • Good scalability and fabrication error tolerance. • This fiber design could be promising candidates toward high-capacity SDM systems. We propose a novel ellipse-assisted ring-core fiber characterized by an elliptical region of low refractive index in the core. The proposed fiber proves effective in eliminating the spatial degeneracy of the LP mn mode groups and keeping the birefringence properties at a low level. This fiber, with optimized structural parameters, can guide 9 modes over the entire C-band. The simulation results show that the effective refractive index difference (Δn eff ) between adjacent modes at 1530–1565 nm falls within the scope of (3.1 ∼ 6.64) × 10 −4 . At the same time, the polarization separation level of each mode is lower than 3.23 × 10 −6 , which is 2 orders of magnitude lower than the degree of spatial mode degeneracy separation. This fiber design has good application prospects in space division multiplexing systems.

Conversion of combined heat and power coal-fired plants to Carnot batteries - Prospective sites for early grid-scale applications

Repurposing fossil fuel-fired plants to electricity storage systems known as Carnot batteries (CB) has been proposed before. This technology provides a prospect of high-power, high-capacity systems for medium and long duration storage. Significant benefits on capital cost from second use of the existing infrastructure and low cost per added MWh are expected to outweigh low round-trip efficiency. Retrofitting large coal plants is still demanding in terms of absolute capital, lack of previous experience and uncertain business. This work proposes smaller coal-fired combined heat and power plants with 50 MWe output as a suitable prospective site for conversion to CB instead of large power plants. Higher overall efficiency with heat providing an additional stream of revenue, plant flexibility, or smaller system size make such application more beneficial, especially for first-of-a-kind installations.Therefore, this paper illustratively investigates the techno-economic prospects of the conversion of a cogeneration coal plant to a CB. The proposed system is described. It is based on direct electrical heating for the power to heat process, thermal energy storage based on either molten salts or gravel packed bed and finally, heat exchangers integrated to operate as steam generators. The sizing of major components is followed by costing. In case of a backpressure turbine, packed bed storage and discharge duration of 5 h the specific cost of electrical storage system is around 200 €/kWhe, while in the case with no heat production and condensing turbine (full condensation regime), it is around 100 €/kWhe. The operation regimes and expected revenue streams from both electricity and heat are evaluated. A comparison with existing technologies is performed and the levelised cost of storage in presented cases varies from 35 to 179 €/MWhe for the fully condensing regime and 35 to 291 €/MWhe for the backpressure cogeneration regime.

A 1.792 Tbps RoF-based PDM-DQPSK DWDM system for high-capacity long-haul 5 G and beyond optical network

This article proposes a high-capacity, cost-effective, and reliable transceiver system for 5 G and beyond optical communication. The system uses differential quadrature phase-shift keying (DQPSK), carrier-suppressed non-return-to-zero (CSNRZ) modulation, duobinary coding, radio over fiber (RoF), and dense wavelength division multiplexing (DWDM) techniques to improve the system’s efficiency. The RoF technology has been implemented using a 3.5 GHz radio frequency in compliance with 3GPP, IEEE, and ITU standards for 5 G communication. The performance of the proposed system has been analyzed using numerical methods in terms of constellation diagram, eye diagram, bit error rate (BER), optical signal-to-noise ratio (OSNR) requirement, and receiver sensitivity. 1.792 Tbps maximum data rate has been achieved in the simulation analysis using the 64-channel DWDM technique. Erbium-doped fiber amplifier (EDFA) compensates for signal attenuation, and dispersion compensating fiber (DCF) compensates for dispersion in a multi-span transmission link. The maximum transmission distance has been extended up to 1600 km at a BER of 10−12. The proposed system shall support high transfer rates and reliable connectivity requirements of 5 G and beyond networks.

10.83 Tb/s Over 800 Km Nonlinear Frequency Division Multiplexing WDM Transmission

Nonlinear frequency division multiplexing (NFDM) transmission scheme has attracted great interest in optical fiber communication systems due to its potential for surpassing the Kerr nonlinearity limit. There have been very active studies on single-channel NFDM transmission systems recently. However, up to now, few experiments have validated the feasibility of applying NFDM into wavelength division multiplexing (WDM) optical communication systems toward high-capacity transmission for wideband coverage. Moreover, the overall performance of the NFDM system is restricted due to many challenges in theoretical design and practical implementation. Novel neural network-based equalization methods contribute to eliminating multi-dimensional crosstalk, hence prompting the NFDM system performance. In this article, we experimentally demonstrate a high-capacity NFDM-WDM transmission system enabled by the newly developed digital signal processing (DSP) algorithms. With data modulation on the continuous spectrum in nonlinear frequency domain, a 25-channel WDM system with polarization division multiplexing (PDM) 16-ary quadrature amplitude modulation (16-QAM) transmitting over 800 km standard single-mode fiber (SSMF) is successfully achieved. To mitigate the undesirable correlations between the nonlinear continuous spectral components, a nonlinear spectrum equalization scheme based on artificial neural network (ANN) is utilized in the receiver side DSP. Through this ANN-based spectrum equalization, a 0.63 dB Q <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> -factor gain is achieved compared to the conventional equalization scheme. A record transmission capacity of 10.83 Tb/s is achieved in a 25-channel WDM system over 800 km SSMF, with a remarkable single-channel line rate of 433.3 Gb/s. Our work reports the highest capacity NFDM-WDM transmission up to date and helps to further explore the inherent ability of NFDM to resist fiber channel nonlinearity.

Seismic performance of high-capacity light wood frame shear walls with three rows of nails

With the increase of building height for light wood-frame construction and seismic loads in National Building Code of Canada 2015, stronger shear wall systems have been facing higher demands, especially for mid-rise wood-frame buildings located in high seismic zones. In collaboration with FPInnovations, a new high-capacity shear wall system with two or three rows of nails was developed. This paper presents the test results of shear walls with three rows of nails. A total of 12 specimens (with two standard shear wall specimens as a reference) were tested under reversed cyclic loading. Test results show that shear walls with three rows of nails have approximately-three times the lateral load resistance of a standard shear wall with the same sheathing thickness, nail diameter and nail spacing. The initial stiffness and ultimate displacement of the high-capacity shear wall are also greater than the comparable standard shear wall. Seismic equivalency to standard shear walls in accordance with ASTM D7989 was also conducted. Although shear walls with three rows of nails have three times of lateral load capacities of a standard shear wall, their design values are less than twice the design values of the standard shear walls. This is mainly due to the fact that a higher over-strength factor has to be used to meet the ductility criteria in ASTM D7989.

Heavy lift semi-submersible ships utilization in offshore wind turbines industry

Many technologies and initiatives have been developed across the world to produce power from renewable resources. One of these technologies is offshore wind power that utilize wind turbines established in water to generate electricity. Offshore wind power generates more electricity per unit of capacity installed due to offshore wind velocity is higher than on land. Wind turbines are difficult to transport because of their huge towers and nacelles, as well as their long, delicate blades, hub, and generator. In order to transport these huge parts specialized ships to handle it and help in its transportation safely with the minimum costs and hazards are needed. Semi-submersible heavy-lift ships are primarily designed to transport extremely large and heavy cargoes, which are loaded using the float-on/float-off method, and large non-floating equipment. A high-capacity ballast system is installed on the heavy lift ships. When loading and unloading cargo, a ballast system is needed to manage heeling and trimming moments. Several accidents have occurred during the submerging process, these accidents result was sinking of many ships. Results are presented and discussed.

Digital Domain Power Division Multiplexing Optical OFDM for Free Space Optical Communication (FSOC) Using 10-GHz Bandwidth Optical Components

We put forward and provide the first illustration of a high capacity and high spectral efficient free space optical communication (FSOC) system using digital domain power division multiplexing orthogonal-frequency-division-multiplexed (DDPD-O-OFDM) signal utilizing 10-GHz class optical components. In the proof-of-concept demonstration, a data rate of 2 × 30.8 Gbit/s can be achieved for each polarization multiplexed wavelength channel, fulfilling the pre-forward-error-correction bit-error-ratio (pre-FEC BER = 3.8 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−3</sup> ). By employing the DDPD-O-OFDM here, the FSOC per channel capacity can be enhanced not only allowing the spectral overlapping of different orthogonal subcarriers, as in the case of OFDM; but also allowing channel multiplexing in the power domain to increase the spectral efficiency. The principle of DDPD-O-OFDM is discussed; and BER and signal-to-noise ratio (SNR) of different DDPD channels are experimentally measured.

Outage Probability and Finite-SNR DMT Analysis for IRS-Aided MIMO Systems: How Large IRSs Need to be?

Intelligent reflecting surfaces (IRSs) are promising enablers for high-capacity wireless communication systems by constructing favorable channels between the transmitter and receiver. However, general, accurate, and tractable outage probability analysis for IRS-aided multiple-input-multiple-output (MIMO) systems is not available in the literature. In this paper, we first characterize the distribution of the mutual information (MI) for IRS-aided MIMO systems by capitalizing on large random matrix theory (RMT). Based on this result, a closed-form approximation for the outage probability is derived and a gradient-based algorithm is proposed to minimize the outage probability with statistical channel state information (CSI). We also investigate the diversity-multiplexing tradeoff (DMT) with finite signal-to-noise ratio (SNR). Based on these theoretical results, we further study the impact of the IRS size on system performance. In the high SNR regime, we provide closed-form expressions for the ergodic mutual information (EMI) and outage probability as a function of the IRS size, which analytically reveal that the benefit of increasing the IRS size saturates quickly. Simulation results validate the accuracy of the theoretical analysis and confirm the increasing cost to improve system performance by deploying larger IRSs. For example, for an IRS-aided MIMO system with 20 antennas at both the transmitter and receiver, we need to double the size of the IRS to increase the throughput from 90% to 95% of its maximum value.

Optical Uplink, D2D and IoT Links Based on VCSEL Array: Analysis and Demonstration

In this paper, vertical cavity surface emitting laser (VCSEL) array is used to establish gigabits/second (Gbps) optical uplink, device-to-device (D2D), and Internet-of-thing (IoT) links, as a supplementary for visible light communication (VLC) and ultra-low latency near-field communication in a typical indoor scenario. The mathematical model based on a modified Monte-Carlo ray-tracing (MMCR) algorithm for VCSEL-based optical wireless communication (OWC) is presented, which takes into account both accuracy and time complexity for the calculation of the channel characteristics including power distribution, impulse response, error analysis, and signal-to-noise ratio (SNR). Simulation firstly takes a global approach to the optical uplink lens design method, compared between Lambertian and Gaussian sources, and then extended six typical line-of-sight (LOS) or non-line-of-sight (NLOS) VCSEL-based OWC models. For demonstration, we adopted a 940-nm VCSEL array and 850-nm single-pixel VCSEL to establish LOS and NLOS systems after measuring the optics-electronics and bandwidth characteristics, respectively. Furthermore, multiple multi-carrier schemes are adopted to improve the OWC performance system based on a 940-nm VCSEL array including uniform-loading orthogonal frequency division multiplexing (OFDM), channel-coded OFDM, bit-loading/ power-allocation OFDM, and OFDM access (OFDMA). Results show that OFDM can effectively decrease the inter-symbol interference (ISI) of the indoor channel and increase the data rate, and the bit/ power-loading method achieves the highest 7.2 Gbps transmission with the bit error rate (BER) within the forward error correction (FEC). All the theoretical and experimental results, for the first time, provide a comprehensive design and optimizing process of VCSEL-based indoor high-capacity OWC systems for future optical uplink, D2D, and IoT applications.

Bidirectional Passive Optical Network Employing Different Line codings/Modulation Formats in Wavelength Reused RSOA Based Symmetrical 10 Gbps

Passive optical networks (PONs) with the integration of multiple channels are the high capacity systems to cater the large number of channels in order to fulfill demands of internet applications. To realize a crosstalk suppressed and cost effective system, an integrated multi channel PON for mitigation of the crosstalk between upstream and downstream channels using different pulse shapes such as Return to zero (RZ), non RZ (NRZ), compressed spectrum RZ (CSRZ), Differential phase shift keying (DPSK) is proposed. Use of reflective semiconductor optical amplifier (RSOA) has been proposed for upstream modulation to make system cost efficient. 2-channel downstream and 2-channel upstream wavelengths are used to exhibits total symmetrical data rate of 10 Gbps. Results revealed that proposed system can support 10 Gbps data rate up to 20 km

Experience of heading and support in super-deep openings in Skalisty Mine of Nornickel’s Polar Division

Currently mineral mining in the world faces continuous growth of mining depth associated with complication of geomechanical conditions and with uncontrollable events induced by confining pressure during mine construction. The reliable prediction and estimation of dynamic events induced by confining pressure is a challenging theoretical and practical problem solvable using analytical, empirical and numerical methods. The article discusses this problem solution as a case-study of heading operations in underground openings RV-1 and RV-2 in Skalisty Mine at the unique depths both in Russia and in Europe: 1800&ndash;2000 m in difficult geological conditions. The operations are carried out by company KANEX Shakhtostroy. The rock mass quality assessment by Barton&rsquo;s index Q shows that it varies from Q = 1&ndash;4 (poor quality) to Q = 0.1&ndash;1 (very poor quality). The in-situ research and numerical modeling determine the fair stress&ndash;strain behavior of rock mass but there exists rockburst hazard and the horizontal stresses exceed the vertical stresses. The maximal horizontal stresses orient nearly north southward, which agree with the monitoring data from shaft SKS-1. In these complex geomechanical conditions, it is recommended to use not stiff mine support systems with high load-bearing capacity but mixed-type support systems with deformation compatibility and high capability to absorb energy. Such engineering solutions, given continuous monitoring and scientific supervision of heading operations, ensure high safety and economic efficiency of mining, which is proved by the positive experience of KANEX Shakhtostroy in super-deep heading operation in RV-1 and RV-2 openings in Skalisty Mine.