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No. 17/2020 (April 27, 2020)
New solar cells for record performance.
Scientists from the US National Renewable Energy Lab (NREL) have produced a six-junction solar cell with the solar conversion efficiency of 47.1%, the highest yet on record. A variation of the same cell has set yet another record, reaching 39.2% efficiency under one-sun illumination. For comparison, the corresponding figure for currently produced monocrystalline panels is ca. 20%. The solar conversion efficiency result measured under concentrated illumination now holds the record among all the solutions of this type. When constructing their cells, NREL researchers relied on III-V materials, which owe their name to the position of relevant elements in the periodic table. Materials of this kind stand out for their high light absorption properties.
John Geisz (left) and Ryan France (right) have produced a solar cell whose efficiency approaches 50%
Each of the cell's six photoactive layers is especially designed to capture light from a specific part of the solar spectrum. Even though it is made up of 140 layers of different materials, the cell is still three times thinner than a human hair. Because of their high performance and manufacturing costs, III-V materials are frequently used to power satellites. A solution of this kind will also be perfect for photovoltaic applications, as long as its manufacturing costs are reduced. One way to do so is to use mirrors that would focus the light down to a point. Using concentrated light allows to reduce the number of required semiconductors and boosts efficiency. While it is possible to build a solar cell with a 50% efficiency, the 100% target is unattainable due to the limits imposed by thermodynamics. Today, the main research hurdle to achieving the 50% mark is the need to reduce the resistive barriers inside the cell that limit its performance.
Gate control in Hikvision's IP Villa intercom systems.
IP Villa door stations have a built-in relay that controls the electric door strike. However, users often need to control not only the door, but also the entrance gateway. To make this possible, the gate station should be connected to an extra control unit (DS-K2M060 G74818) via the RS-485 interface. This allows to control the electric door strike and the entrance gateway via home-based monitors, the iVMS-4200 client software, or the Hik-Connect smartphone app.
Block diagram of an IP video door system
that controls the entrance gate.
that controls the entrance gate.
How to export a list of iVMS-4200-managed devices to another PC?
Devices managed by the client software make up a list, which, along with other iVMS-4200 settings, can be transferred between computers. This is also useful when installing a software upgrade, since the app must be uninstalled in the process. In order to generate the configuration file, click the Main Menu button, and select System → Export Configuration File.
iVMS-4200 is a client software designed for the management and control of Hikvision DVRs/NVRs (IP, TurboHD), video intercoms, access control solutions, decoders, etc. It allows users to maintain easy and convnient control over all systems, offering live IP camera viewing, remote playback, remote configuration, alarm events, two-way audio transmission, e-maps, HDD recording and more. The app can manage up to 256 devices and support simultaneous footage from up to 64 cameras on 4 monitors.
When should you buy an LTE antenna?
When the base station is far away from the mobile device, signal strength is often compromised and an appropriate outdoor antenna may have to be connected to the modem to improve it. Before you choose an antenna, however, verify the parameters of the LTE signal picked up by your modem. To do so, run the network diagnostic panel available in the router/modem software and compare the parameters with the values presented below.- RSRP (dBm) - (Reference Signal Receive Power) - measure of the signal strength.
- more than -79 dBm - very good signal strength,
- from -80 dBm to -90 dBm - good signal strength,
- from -91 dBm to -100 dBm - poor signal strength. Need for an outdoor antenna or finding a better location of the modem
- less than -100 dBm - very poor signal strength. It is necessary to use an outdoor antenna
- RSRQ (dB) - (Reference Signal Received Quality) - measure of the signal quality.
- more than -9 dB - very good,
- from -10 dB to -15 dB - good,
- from -16 dB to -20 dB - bad. Need for an outdoor antenna or finding a better location of the modem
- less than -20 dB - very bad It is necessary to use an outdoor antenna
- SINR (dB) - (Signal to Interference plus Noise Ratio) - measure of signal quality with respect to interference.
- more than 21 dB - very good,
- from 13 dB to 20 dB - good,
- from 0 dB to 12 dB - bad. It is necessary to use an outdoor antenna
- less than 0 dB - very bad.It is necessary to use an outdoor antenna
- RSSI - Received Signal Strength Indicator
- more than -73 dBm - very good,
- from -75 dBm to -85 dBm - good,
- from -87 dBm to -93 dBm - bad. Need for an outdoor antenna or finding a better location of the modem
- less than -95 dBm - very bad. It is necessary to use an outdoor antenna
Coaxial cable screening classification.
Cabling is one of the most important parts of any TV system. To be transmitted successfully, the signal needs to be isolated from interfering signals generated by power lines or parallel TV and SAT cables (crosstalk). A good coaxial cable should be characterized by low insertion loss and high screening efficiency. The latter is tested in the 5-3000 MHz range and typically takes values from 45 to more than 120 dB. For high screening efficiency in SMATV systems, we recommend using DIPOLNET Tri-shield E1220 cables.Classes of screening efficiency according to EN50117:
| Class | 30-1000 MHz [dB] | 1-2 GHz [dB] | 2-3 GHz [dB] |
| C | >75 | >65 | >55 |
| B | >75 | >65 | >55 |
| A | >85 | >75 | >65 |
| A+ | >95 | >85 | >75 |
| A++ | >105 | >95 | >85 |
Screening efficiency of Tri-Shield DIPOLNET E1220 in 30-3000 MHz range
and the requirements for class A and class A+
and the requirements for class A and class A+
The core alignment option ensures the most precise fiber positioning and guarantees the best outcomes (low attenuation) even when you splice two low-quality fibers with a non-centric core. Splicers that rely on the core alignment mechanism must be equipped with a high-quality optical system, high-precision stepper motors responsible for fiber positioning, and appropriate software.
Core alignment fusion splicers can be divided into 4-motor and 6-motor models. The first 4 motors are responsible for fiber positioning along the vertical and horizontal axes (2 on each side). Available in the best splicers, motors no. 5 and 6 enable autofocus, which sharpens the image of the core or the cladding, depending on the alignment option. In contrast, 4-motor splicers have a fixed focus point. Interestingly, while the focus point of cladding alignment splicers is adjusted to the cladding, that of the core/cladding alignment models falls between the core and the cladding. As a result, the cladding will not be in the sharpest focus, and the same will hold true for the core. This focus point adjustment is a compromise between achieving a sharp-focused image of the core and an eye-friendly overall view of the fiber on the screen. In this case, core alignment is not as precise as in 6-motor fusion splicers (assuming that both models are fitted with the same optical system).
 | Metal Housing/Box: GFM-12(F) L54112 has been designed for use in various conditions. The electrostatically powder-coated installation box is resistant to corrosion as well as to low and high temperatures in an outdoor environment. | |
 | Stainless Steel Band (19x0.7mm, 50m, in dispenser) E88828 is placed in a convenient plastic dispenser that acts as a packaging. The band is used, among others, to install slings, to make straps for fastening brackets and frames on poles. Made of AISI 430 stainless steel. | |
 | Steel Banding Tool (Telcom AQL type, reinforced) E8581 is designed for tensioning and cutting the steel banding used to assemble brackets, mounts and other accessories for the construction of fiber optic lines. The tool can be used with 10-20 mm wide steel bands.. | |
Uploading camera screenshots to an FTP server. Hikvision IP cameras and NVRs allow to save screenshots on a remote server. The screenshots can be taken at specific time intervals (e.g. every second) and used e.g. to create basic surveillance video websites or to visualize the progress of road works. Screenshots can also be triggerd by an alarm event, such as motion detection...>>>more
IP camera signal in a DTT antenna system
