12 smart doorbells to watch over your front stoop 13 Photos Smart Home Gadgets Video Cameras Security Tags These devices sound like they’d come in handy and would do a good job at deterring theft. What are some other reasons you’d use them? Maybe you don’t want to walk all the way to the front door just to find out your visitor was a solicitor. Maybe you have mobility issues. Or maybe you want to catch creeps like this guy. There’s a wide array of reasons and a wide array of smart doorbells to choose from.So we want to know: Do you own a smart doorbell already? Has it paid off? Have you caught a thief in the act? If so, please share! If not, do you find yourself wanting one? What features are you looking for? If you don’t want one, how come? Check out the poll below and cast your vote to answer these questions and more. If you’d like to explain your vote further, please join us in the comments.Check out previous installments of CNET Asks here, and cast your votes on a wide range of topics. If there is a particular question you’d like to see asked, or if you’d like a shot at being featured in a future edition, join us at CNET Member Asks and submit your topic idea. Share your voice 1:58 Now playing: Watch this: Read more: 7 smart doorbells that make screening visitors oh-so easyRead also: Netgear adds a smart doorbell to its Arlo home security lineup I was taught as a child not to open the door to just anyone and I still think that’s a good rule. And now there’s a device that makes it easier than ever to keep strangers out. The smart doorbell concept is simple: Someone rings the bell or approaches your door and you get a push notification to your phone — which then shows you a live video of your front step. Some smart doorbells allow you to chat with your visitor through your phone and a speaker inside the buzzer. Some allow you to unlock your door from your phone. One of the most important features is the motion-activated camera, which can help guard against would-be porch pirates who could be after your deliveries. Comments 17 Things to consider when choosing between brands (other than cost) include the live view resolution, the latency between doorbell and push notification and the two-way audio. You can check out our list of smart doorbells and their respective features here. CNET Asks 9 smart doorbells to try now
Two elderly people were killed when a truck hit them in Chamta bus stand area of Nandail upazila on Wednesday morning.The deceased are Sirajuddin, 75, of Atkapara village, and Tofazzal Hossain, 70, of Kutubpur village of the upazila.According to witnesses, a Kishoreganj-bound speeding truck ran over the victims on Mymensingh-Kishoreganj highway, killing them on the spot around 8:00am.Agitated locals blocked the highway protesting the incident.Later police rushed to the spot and brought the situation under control.
Most computers today store memory electronically, by maintaining a certain voltage. In contrast, a new kind of memory that stores data thermally, by maintaining temperature, is being investigated by researchers Lei Wang of the National University of Singapore and the Renmin University of China, and Baowen Li of the National University of Singapore and the NUS Graduate School for Integrative Sciences and Engineering. Citation: Scientists Propose Thermal Memory to Store Data (2009, January 7) retrieved 18 August 2019 from https://phys.org/news/2009-01-scientists-thermal-memory.html Explore further This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. In recent years, thermal research has improved scientists’ understanding of heat conduction on a molecular level. Scientists have created theoretical models of some thermal devices, including a thermal transistor and logic gate, both by Wang and Li in 2006 and 2007, respectively. This kind of work has opened the doors to the new subject of “phononics” – the science and engineering of processing information with heat. In the current study, Wang and Li take the field of phononics one step further and show the feasibility of a thermal memory that can store data with heat. The scientists predict that such a heat memory could be experimentally realized in the foreseeable future with rapidly advancing nanotechnology. Their work is published in a recent issue of Physical Review Letters.As Wang and Li explain, any thermally insulated system might be a candidate for thermal memory since it maintains its temperature (data) for a long time. Still, any system will face the challenge of unavoidable perturbation when the temperature is measured (when the data is read). Due to energy exchange between the thermometer and the system, the system won’t be able to naturally recover its original temperature after the data reading. To solve this problem, the researchers suggest using a thermal circuit capable of producing two steady states, which is connected to a power supply from an external heat bath.Wang and Li’s thermal memory consists of a single particle sandwiched between two lattice segments, each consisting of about 50 atoms. These left and right segments are connected to heat baths at different fixed temperatures, and the central particle is connected to a control heat bath that can be set to “on” or “off.” The particle’s chosen state can remain unchanged for a long time even after the heat bath is removed. The particle and the segments are also weakly coupled together by harmonic springs. This memory system, the researchers explain, can perform a complete write-read process. The “writer” is made of a lattice of about 10 particles, connected to the central particle by a linear spring. The other end of the writer is connected to a heat bath. Depending on the supply from the heat bath, the writer can either cool the particle to the off state or heat it to the on state. To read the data, a thermometer (made of the same lattice as the writer) is connected to the central particle. Unlike the writer, the reader is not connected to a heat bath, but is set to a temperature between the on and off states. If the particle is in the on (hot) state, the reader will heat up; if the particle is off (cool), the reader cools down. Of course, the particle’s temperature will also change when exposed to the medium-temperature reader. But the heat baths connected to the left and right segments will either absorb the particle’s excess heat or warm the particle, so that the particle recovers its original temperature (and state) in either case.The researchers calculated that, when the writer is removed, the system can maintain its state for a relatively long time, although an ideal thermal memory is impossible due to thermal fluctuations. However, by refreshing the data (similar to how voltage data is regularly refreshed in dynamic random access memory [DRAM]), thermal memory can achieve a lifetime long enough for practical applications. The scientists also noted that the lifetime can be extended further by combining identical memories together.By theoretically demonstrating the possibility of a thermal memory that is self-recoverable after being read by a thermometer, Wang and Li hope that computers will one day reap the benefits of thermal technology.More information: Wang, Lei and Li, Baowen. “Thermal Memory: A Storage of Phononic Information.” Physical Review Letters 101, 267203 (2008).© 2009 PhysOrg.com Controlling heat and particle currents in nanodevices by quantum observation