A clock is an instrument to indicate, keep, and co-ordinate time. The word clock is derived ultimately (via Dutch, Northern French, and Medieval Latin) from the Celtic wordsclagan and clocca meaning "bell". A silent instrument missing such a striking mechanism has traditionally been known as a timepiece. In general usage today a "clock" refers to any device for measuring and displaying the time. Watches and other timepieces that can be carried on one's person are often distinguished from clocks.
The clock is one of the oldest human inventions, meeting the need to consistently measure intervals of time shorter than the natural units: the day, the lunar month, and theyear. Devices operating on several physical processes have been used over the millennia. A sundial shows the time by displaying the position of a shadow on a flat surface. There are a range of duration timers, a well-known example being the hourglass. Water clocks, along with the sundials, are possibly the oldest time-measuring instruments. A major advance occurred with the invention of the verge escapement, which made possible the first mechanical clocks around 1300 in Europe, which kept time with oscillating timekeepers like balance wheels. Spring-driven clocks appeared during the 15th century. During the 15th and 16th centuries, clockmaking flourished. The next development in accuracy occurred after 1656 with the invention of the pendulum clock. A major stimulus to improving the accuracy and reliability of clocks was the importance of precise time-keeping for navigation. The electric clock was patented in 1840. The development of electronics in the 20th century led to clocks with no clockwork parts at all.
The timekeeping element in every modern clock is a harmonic oscillator, a physical object (resonator) that vibrates or oscillates repetitively at a precisely constant frequency.This object can be a pendulum, a tuning fork, a quartz crystal, or the vibration of electrons in atoms as they emit microwaves. Analog clocks usually indicate time using angles. Digital clocks display a numeric representation of time. Two numeric display formats are commonly used on digital clocks: 24-hour notation and 12-hour notation. Most digital clocks use electronic mechanisms and LCD, LED, or VFD displays. For convenience, distance, telephony or blindness, auditory clocks present the time as sounds. There are also clocks for the blind that have displays that can be read by using the sense of touch. Some of these are similar to normal analog displays, but are constructed so the hands can be felt without damaging them. The evolution of the technology of clocks continues today.
A mobile phone is a portable telephone that can make and receive calls over a radio frequency carrier while the user is moving within a telephone service area. The radio frequency link establishes a connection to the switching systems of a mobile phone operator, which provides access to the public switched telephone network (PSTN). Most modern mobile telephone services use a cellular network architecture, and therefore mobile telephones are often also called cellular telephones or cell phones. In addition to telephony, 2000s-era mobile phones support a variety of other services, such as text messaging, MMS, email, Internet access, short-range wireless communications (infrared, Bluetooth), business applications, gaming, and digital photography. Mobile phones which offer these and more general computing capabilities are referred to as smartphones.
The first handheld mobile phone was demonstrated by John F. Mitchell and Martin Cooper of Motorola in 1973, using a handset weighing c. 4.4 lbs (2 kg). In 1983, the DynaTAC 8000x was the first commercially available handheld mobile phone. From 1983 to 2014, worldwide mobile phone subscriptions grew to over seven billion, penetrating 100% of the global population and reaching even the bottom of the economic pyramid. In first quarter of 2016, the top smartphone manufacturers were Samsung, Apple and Huawei (and "[s]martphone sales represented 78 percent of total mobile phone sales").
A USB flash drive, also variously known as a USB drive, USB stick, thumb drive, pen drive, flash-disk, or USB memory, is a data storage device that includes flash memory with an integrated USB interface. USB flash drives are typically removable and rewritable, and physically much smaller than an optical disc. Most weigh less than 30 grams (1.1 oz). Since first appearing on the market in late 2000, as with virtually all computer memory devices, storage capacities have risen while prices have dropped. As of March 2016, flash drives with anywhere from 8 to 256 GB are frequently sold, and less frequently 512 GB and 1 TB units. Storage capacities as large as 2 TB are planned, with steady improvements in size and price per capacity expected. Some allow up to 100,000 write/erase cycles, depending on the exact type of memory chip used, and have a 10-year shelf storage time.
USB flash drives are often used for the same purposes for which floppy disks or CDs were once used, i.e., for storage, data back-up and transfer of computer files. They are smaller, faster, have thousands of times more capacity, and are more durable and reliable because they have no moving parts. Additionally, they are immune toelectromagnetic interference (unlike floppy disks), and are unharmed by surface scratches (unlike CDs). Until about 2005, most desktop and laptop computers were supplied with floppy disk drives in addition to USB ports, but floppy disk drives have become obsolete after widespread adoption of USB ports and the larger USB drive capacity compared to the 1.44 MB 3.5-inch floppy disk.
USB flash drives use the USB mass storage device class standard, supported natively by modern operating systems such as Windows, Linux, OS X and other Unix-like systems, as well as many BIOS boot ROMs. USB drives with USB 2.0 support can store more data and transfer faster than much larger optical disc drives like CD-RW or DVD-RW drives and can be read by many other systems such as the Xbox 360,PlayStation 3, DVD players, automobile entertainment systems, and in a number of handheld devices such as smartphones and tablet computers, though the electronically similar SD card is better suited for those devices.
A flash drive consists of a small printed circuit board carrying the circuit elements and a USB connector, insulated electrically and protected inside a plastic, metal, or rubberized case which can be carried in a pocket or on a key chain, for example. The USB connector may be protected by a removable cap or by retracting into the body of the drive, although it is not likely to be damaged if unprotected. Most flash drives use a standard type-A USB connection allowing connection with a port on a personal computer, but drives for other interfaces also exist. USB flash drives draw power from the computer via the USB connection. Some devices combine the functionality of a portable media player with USB flash storage; they require a battery only when used to play music on the go.
Product details of LED Office Desk Wooden Digital Alarm Clock(Black Bottom+Green Word)
Away from the radiation,low carbon life---stop using the cel phone as your alarm in daily life. During 18:00~7:00 this time,the brightness of the display will weaken. 12/24-hour Format selectable. (initial mode: 24 hour),this mode can meet different person’s habits of looking at time. After opening the alarm mode,time,data and temperature will alternately display once time and the LED would auto close and entering the power saving mode. Shows the time and date in addition to getting you out of bed with an extremely shrill noise. A little tap to the clock or when the Voice is greater than 60 decibels,the LED would start the display function. Material: Composite panels Powered by: 3 x AAA batteries (Not included)/USB cable (Included) Size:125 x 45 x 65 mm.100% Brand New and High Quality.
Type:Black Bottom+Green Word Has two display mode: 1.Display time only 2.Time,temperature and date alternately display.
Product details of Sandisk Cruzer Dial 16 GB Flashdrive
Transferring files from one device to another can be a tiring task. When your day is filled with work and other important things, a dependable USB can be your savior. Let the Sandisk Cruzer Dial 16GB Flash Drive be your go-to USB for all your file transfers.
Its huge capacity at 16GB allows you to bring many of your files anywhere, conveniently. Plus, you’re assured that they will stay there without the fear of getting accidentally opened or deleted. The SanDisk SecureAccess feature allows you to save files on a private folder with 128-bit AES encryption software, making it easy to password-protect critical files. With its unique dial that opens and closes the retractable connector, the Cruzer Dial offers reliable storage in a design that’s both handy and handsome.
Product details of Yoobao 10400mAh Magic Cube Power Bank YB647 (Black)
Introducing the fully loaded yet very affordable Lenovo A390 Smartphone. Featuring a Dual Core processor and Dual SIM, this 4” beauty offers enhanced multitasking capabilities. A 5MP camera and an Android 4.0 operating system with access to more than 700,
Product details of Mini Bluetooth Speaker (Silver)
Amp your music experience with anywhere you go with the AF Mini Digital Bluetooth Speaker. Wired or wireless, it has the connectivity to suit your preference. Grab your Bluetooth capable multimedia player and the Mini Bluetooth Speaker will take care of your audio needs. You can also connect your non Bluetooth gadgets with USB port.
Wireless portability This handy speaker allows you connect wirelessly and stream your music and movies over the air. Because they're really small, they're very light and easy to carry around. It has a strong signal with working range of up to 10m.
Long hours of play With a rechargeable battery installed, you get over 3 hours of audio streaming before you plug it again. This large capacity maximizes your music enjoyment.
Efficient option If Bluetooth isn't quite your cup of tea, it comes with a standard USB and audio cable that you can connect-it saves a lot on the battery this way. The AF Mini Bluetooth Speaker is the perfect companion to the dedicated audiophile or anyone who wants to maximize the use of their gadget.
