Hello!! It's Joseph

2024年12月21日17时21分 冬至日係北半球全年白晝最短，夜晚最長的一日 圭表：正午日影最長。 從冬至到下一個冬至的時間稱為一「歲」，而從農曆正月初一到下一年正月初一的時間稱為一「年」。 冬至，阴极之至，阳气始生，日南至，日短之至，日影长之至，故曰“冬至”。 【古人的新年】冬至是二十四节气中最早制订出的一个，早在上古时期，中国人就已经用土圭观测太阳，测定出了冬至。古人认为自冬至起，白昼一天比一天长，阳气开始回升，代表下一个循环开始，是大吉之日。 人们最初过冬至节是为了庆祝新的一年的到来。据记载，周秦时代冬十一月为正月，所以 贺冬与拜岁相同 ，并没有分别，人们以冬至为岁首过新年。直到汉武帝采用夏历后，把正月和冬至分开，从此人们开始专门过“冬至节”是自汉代以后才有，盛于唐宋，相沿至今。 Reference: Ytliu0   Weixin

 Calendar form( in BJT UT+8) Text form Reference: Weixin

 Glass electrode

 日本風格 from littlepig： From sun locator app:

Brunwater calculator work best for me. Work by dilution, ie to lower acidicity,( higher pH values) step by step Do by making 350 ml then dilute to 3500 ml(target) Sanity check: Rinse ph meter with water when pH readings is doubtful. Measure again with  tap water, and calibration liquids From experience, initial 350ml is around pH 2.5 or 2.6 When making 3500 as final volume, start by add 80% to 85% of calculated water amount, ie 2800 ml in this case Add the required salts, eg gypsum and calcium chloride before adding more water. Stir to make sure all is dissolved  Add 50ml every time to watch how pH values go up ( less acidic) PH starts ~ 4.6 to 4.8 Every 50 to 100 ml lower acidicity by ~0.1(pH values go up 0.1) The trend is not linear,but increase in steps  I think ph 5.4 or 5.5 is good enough. My cheap pH meter can have a deviation of 0.2 or maybe more. Double check with ph paper when reaching ~5.0 Tips Constant stirring  Read after 15 seconds Cleanse the pH meter ...

CaSO4 · 2H2O. Dihydrate  生石膏粉 现在药房出售的生、熟石膏均为白色的粉末状，不太好鉴别。简易的区分方法为：取石膏粉末10克，加水约15毫升，搅拌均匀。 放置10分钟后，若呈干性黏团块状者是熟石膏，而呈湿性散渣状者，则为生石膏。 硫酸钙化学式CaSO4。熔点1450℃，相对密度2．96，难溶于水???。它的二水合物CaSO4•2H2O俗称石膏（或生石膏）二水硫酸鈣。 gypsumchina 半水合物CaSO4•1/2H2O hemihydrate称熟石膏（或烧石膏）。(TB 最常買到的是熟石膏，甚至把熟石膏當作生石膏賣）plaster of paris. 二水 vs 無水 石膏加热至128℃，失去大部分结晶水，变成熟石膏；163℃以上，结晶水全部失去。熟石膏粉末与水混合后有可塑性，但不久就硬化重新变成石膏。此过程放出大量热并膨胀，因此可用于铸造模型和雕塑。 硫酸钙和石膏可用作联合制造硫酸和水泥的原料，还可做油漆的白颜料、纸张的填料 熟石膏粉用作豆腐的凝结剂。 Gypsumchina Gypsum is moderately water-soluble (~2.0–2.5 g/L at 25 °C)and, in contrast to most other salts, it exhibits retrograde solubility, becoming less soluble at higher temperatures.  When gypsum is heated in air it loses water and converts first to calcium sulfate hemihydrate (bassanite, often simply called "plaster")  and, if heated further, to anhydrous calcium sulfate (anhydrite).  As with anhydrite, the solubility of gypsum in saline solutions and in brines is also strongly dependent on sodium chloride (common table ...

 From NAOJ : HKT(UT+8) From HKO

 Sang-Hyeon Ahn (韓國天文硏究院) 2020.12.05. @天文文化研究会 Political transition  高麗->朝鮮 朝鮮世宗  1397-1450 禮樂制度 The morality was well described by a sentence in a famous Chinese classic called lizi (禮記):  “大樂與天地同和. 大禮與天地同節,” which is translated as “Great music harmonizes with the Nature  Great rites follows the order of the Nature.” Here the concept of harmonization is related with politics, and that was realized or demonstrated by ancestral rites 祭祀. Music is an important part in performing rituals 儀式. Music can unite people! Moreover, the concept of the order of Nature is realized by an exact definition of seasonal grants 節氣 that is calendar. Calendar can give public order to the people! 渾儀，渾象，簡儀，小簡儀 日星定時儀： Its structure consists of three rings on a cross, called the Jucheondo-bunhwan (周天度分環), Ilgubaekgak-hwan (日晷百刻環), and Seonggubaekgak-hwan (星晷百刻環), and it is made based on the altitude (latitude) of the North Pole in Hanyang. The north and south are ruled by aligning th...

Funny calibration guide from timemore: No of bits of ADC is more important Usually it's 24 bits eg in HX711,  looks like this 24 bit ADC will give about 14 to 15 noise-free bits.  ie range is say 2^14 to 2^15 usable. Arduino forum   Eg a 0.01g minimum gradation  The range is theoretically 0.01 to 163.84g, or 327.68g  so if it can measure up to 200g, the repeatability in this range is pretty safe. Min grad can be misleading  起稱範圍 is more important  See reply below: Eg this Balance claimed a 0.001g (1mg) But initial is 0.005g If possible, choose one with one more decimal digit. Eg if you want to measure up to 0.01g, choose one that displays 0.001g Btw, those cheap balance( under¥100), most can only repeatedly measure up to 0.01g, even it says 0.001g accuracy  The weight 砝碼 provided with the kit is usually 100g ,M grade. This is pretty meaningless(~¥7) But if you want to measure 0.1g or less, better to use at least F2 grade weight Hysteresis of load ...

Contributions Inventing pH scale(1909) purifying lager yeast (1883) at Carlsberg laboratory, Emil C. Hansen, discovered a method of isolating yeast so that brewers could use fresh yeast during every fermentation. This yeast was named as Saccharomyces Carlsbergensis and it was distributed freely to anyone including other brewers until 1988.  Role of  enzymes  Malt roasting Reference  Carlsberg group   Ontario  pressbook

Muhammad Ibn Abi Bakr, Isfahan 1221/2 AD Front: Back: Composite: Composite back: Drawing: Reference  HSM UK

 “宋金”蔷薇水蒸馏器 1975年，河北省青龙县境内出土了一件金代铜胎烧锅，是当时用来蒸馏花露水。 酒文化 Baike

  Written by a local HK guy, maybe the only one so far. Using 2 vessel brewhouse for setup.  Minimum amount of hardware. No fuss Those calculations are ok, but not much explanation  Eg temperature of strike water,  how 0.41 is derived. Hint: specific heat capacity  This is actually based on: equation for heat transfer capacity Q = mcΔT John Palmer's howtobrew book: Initial Infusion Equation: Strike Water Temperature Tw = (.2/r)(T2 - T1) + T2 Mash Infusion Equation: Wa = (T2 - T1)(.2G + Wm)/(Tw - T2) where: r = The ratio of water to grain in quarts per pound. Wa = The amount of boiling water added (in quarts). Wm = The total amount of water in the mash (in quarts). T1 = The initial temperature (¡F) of the mash. T2 = The target temperature (¡F) of the mash. Tw = The actual temperature (¡F) of the infusion water. G = The amount of grain in the mash (in pounds). The infusion water does not have to be boiling, a common choice is to use the sparge water at 170¡F. Then...

  6 cm tall. Using 3.5cm alu square  BLDC motor： 27mm外转子高速无刷电机，BL2717无刷电机，稀土中强磁外转子，带动平衡矫正，双滚珠轴承，电机标称电压14.4V，最大功率约30W，峰值最大电流2.8A，电机支持正反转/PWN信号调速/急停/信号反馈FG输出。電壓範圍 7 - 14V 电机内置驱动电路，支持PWM信号无极调速，14V电压测试空载转速PWM信号调节约100-10000转。 Now set at 9V. PWM board:

Using focal length of  100mm f/2 as example  Double gauss: Double gauss performance: Sonnar performance: Datasheet of sonnar f/4 13.5 cm Zeissikonveb : If you look at the data sheet above, you will be amazed: no heavy or even very heavy crown is needed, no barite flint or similar "exotic" glasses. The two front convex lenses are made of simple boron crown BK7 - one of the cheapest crown glasses that can be produced in large quantities. However, it has decisive advantages if you do not need particularly high refractive indices: it only splits the light into its primary colors to a small extent, which makes chromatic correction easier. Since the 1890s, it had become the standard material for prisms due to its high transparency and, due to its low thermal expansion, it was also often used as a base for mirrors. Only the subsequent flint glass F9 was relatively new in the glass catalog. The result is barely perceptible spherical zones and a practically completely flat image field...